— 


DEPi 

Gift 


No. 


LESSONS  IN 

FOR  BEGINNERS 


INCLUDING 


BRIEF  AND   PLAIN   DESCRIPTIONS   OF   THE   MOST 

IMPORTANT   PARTS  OF  THE   HUMAN  BODY 

AND    THE   ACTION   OF   ALCOHOL 

AND   OTHER   STIMULANTS 


BY 


GEOKGE   D.  LIND,   M.D. 

AUTHOB  OP  "  LESSONS  IN  PHYSIOLOGY,"  ETC. 


DANVILLE,    INDIANA 

INDIANA   PUBLISHING   COMPANY 

1897 

NOW  PUBLISHED  BY 
Hinds,  Noble  &  Eldredge,  31-33-35  West  15th  Street,  N.  Y, 


*«„  -a 


RIGDON'S 


Grammar  of  the  English  Sentence  and  Introduction  to 

Composition 85  c. 

English  Grammar  for  Beginners 40  c. 

English  Grammar  for  the  Common  School  .      .      .      .  60  c. 

Outlines  in  Grammar  and  Discussions  of  the  Infinite  Verbs  25  c. 

Analysis  of  the  English  Sentence  with  Diagrams    .      .  75  c. 

Methods  in  Arithmetic .  25  c. 

Outlines  in  Psychology  (In  Preparation) 


LINO'S 

Lessons  in  Physiology $1.00 

Lessons  in  Physiology  (College  Edition) 1.25 

Lessons  in  Physiology  for  Beginners 60 


INDIANA   PUBLISHING   COMPANY. 


EDUCATION 


COPYRIGHT,  1892, 
BT  JONATHAN  RIGKDON. 


TYPOGRAPHY  BY  J.  S.  CUSHING  &  Co.,  BOSTON. 
PRESSWORK  BY  BERWICK  &  SMITH,  BOSTON. 


AUTHOR'S   PREFACE. 


To  write  a  book  for  beginners  in  any  branch  of  knowl- 
edge is  no  easy  task.  The  author  realizes  the  difficulties 
in  the  way,  and  freely  admits  his  inability  to  produce 
a  perfect  work  in  this  line.  Years  of  experience,  how- 
ever, in  teaching  Physiology  to  all  grades  of  pupils,  from 
the  child  of  ten  years  to  the  medical  student  of  twenty- 
five,  have  qualified  him,  in  part,  for  a  task  of  this  kind. 
Therefore,  without  further  apology,  this  little  book  is 
submitted  to  the  public  to  stand  on  its  intrinsic  merits. 

The  author  believes  that  the  following  lessons  will 
not  only  interest  boys  and  girls  and  lead  them  to  a  fur- 
ther study  of  this  important  subject,  but  will  help  them  to 
form  habits  in  youth  that  stand  for  health  and  strength 
of  body  and  mind  in  manhood  and  womanhood. 

GEOKGE  D.   LIND. 
ST.  Louis,  U.S.A.,  April,  1892. 

iii 


541359 


TABLE   OF   CONTENTS. 


[This  table  is  not  intended  for  reference,  but  merely  to  show  at  a  glance 
the  general  nature  of  the  subjects  discussed.  For  ready  reference  to  any 
particular  part  see  Alphabetical  Index  at  close  of  volume.] 

LESSON  PAGE 

I.     INTRODUCTION 1 

II.     DRY  BONES 3 

III.  THE  USES  OF  BONES 8 

IV.  THE  BONES  OF  OUR  BODIES  .     .     . 9 

V.     CARE  OF  OUR  BONES 14 

VI.     THE  JOINTS 16 

VII.     THE  MUSCLES 18 

VIII.     THE  USES  OF  MUSCLES 22 

IX.     CARE  OF  MUSCLES 24 

X.     BONES  AND  MUSCLES  —  A  KEVIEW 29 

XI.     THE  MOUTH  AND  TEETH 31 

XII.     THE  ROAD  TO  THE  STOMACH 35 

XIII.  THE  STOMACH 37 

XIV.  THE  INTESTINES 39 

XV.     THE  ALIMENTARY  CANAL  —  A  REVIEW      ....  41 

XVI.     THE  LIVER,  PANCREAS,  AND  SPLEEN      .     :     .     .     .  43 

XVII.     DIGESTION ..47 

XVIII.    FOOD  AND  DRINK 50 

XIX.     CARE  OF  THE  DIGESTIVE  ORGANS 53 

XX.     REVIEW  OF  DIGESTIVE  SYSTEM 57 

XXI.     THE  HEART 59 

XXII.     THE  BLOOD  VESSELS 64 

XXIII.  THE  BLOOD  AND  HOW  IT  CIRCULATES 70 

XXIV.  THE  LYMPHATICS 74 

v 


VI 


CONTENTS. 


LESSON  PAGE 

XXV.  HOW    TO    CARE   FOB    CIRCULATORY    SYSTEM        .       .  76 

XXVI.  REVIEW  OF  THE  CIRCULATORY  SYSTEM      ...  80 

XXVII.  THE  MACHINERY  OF  BREATHING 82 

XXVIII.  HOW   AND    WHY    WE   BREATHE 86 

XXIX.  HOW    TO    CARE    FOR    THE    BREATHING    ORGANS       .  89 

XXX.  REVIEW  OF  THE  RESPIRATORY  SYSTEM     ...  93 

XXXI.  THE  SKIN 94 

XXXII.  HAIR,  KAILS,  AND  GLANDS  OF  THE  SKIN     .     .  96 

XXXIII.  Mucous  AND  SEROUS  MEMBRANE 98 

XXXIV.  SECRETION,  EXCRETION,  AND  ABSORPTION      .     .  100 
XXXV.  BATHING  AND  CLEANLINESS 103 

XXXVI.  THE  BRAIN  AND  SPINAL  CORD 105 

XXXVII.  THE  NERVES 109 

XXXVIII.  How  THE  BODY  is  GOVERNED 112 

XXXIX.  CARE  OF  THE  NERVOUS  SYSTEM 116 

XL.  REVIEW  OF  THE  NERVOUS  SYSTEM 118 

XLI.  THE  EYE 121 

XLIL  How  WE  SEE 125 

XLIII.  THE  EAR 128 

XLIV.  How  WE  HEAR 130 

XLV.  SMELL,  TASTE,  AND  TOUCH  ........  132 

XL VI.  CARE  OF  THE  SENSE  ORGANS 134 

XL VII.  ALCOHOL  AND  ITS  EFFECTS 137 

XL VIII.  TOBACCO  AND  ITS  DANGER 140 

XLIX.  OTHER  STIMULANTS  AND  NARCOTICS     .     ...  142 

L.  WHAT  TO  DO  IN  EMERGENCIES 145 

INDEX                                                                                    .     .  151 


LESSONS   IN  PHYSIOLOGY 

FOR   BEGINNERS. 

LESSON  1. 

Introduction. 

[NOTE.  —  This  lesson  may  be  simply  read  as  an  exercise,  and  not  assigned 
for  study,  if  the  teacher  think  proper.] 

1.  What  is  Physiology?  — You  have  already,  no  doubt, 
some  idea  of  the  meaning  of  the  word.     You  suppose  it 
is  in  some  way  connected  with  a  knowledge  of  the  human 
body.     You  have  seen  the  word  Anatomy.     It  means  the 
study  of  the  parts  of  the  ~body,  how  it  is  put  together, 
and  what  it  is  made  of.     The  word  Physiology  is  prop- 
erly applied  to  a  knowledge  of  how  the  parts  of  the  body 
act,  or  the  working  of  the  machine,  if  we  may  so  call 
the  body.      The   word    Hygiene   has    also  probably  met 
your  eyes.     It  refers  to  the  art  of  taking  care  of  the  ~body 
and  preserving  its  health.      For  the  sake   of  simplicity 
we  generally  call  the  study  of  Anatomy,  Physiology,  and 
Hygiene  by  one  name,  —  "  Physiology." 

2.  A  Bit  of  History. — The  ancients  knew  very  little 
about   the   human  body.      Hippocrates    lived  400  years 
before  the  birth  of  Christ,  and  because  he  knew  a  little 
about  bones  and  muscles  and  advised  the  sick,  he  was 
called  the  "  Father  of  Medicine  "  ;  but  in  a  few  months 
of  study  you  may  be  able  to  know  a  great  deal  that  Hip- 

i 


,      o       PHYSIOLOGY    FOR   BEGINNERS. 


pocrates  did  not  know.  For  many  hundreds,  of  years 
very  little  was  added  to  the  knowledge  of  Hippocrates. 
In  the  year  1619  William  Harvey,  an  English  surgeon, 
first  discovered  that  the  blood  made  a  complete  circuit 
of  the  body.  Since  that  time  progress  in  knowledge  has 
been  gradual  and  rapid,  and  to-day  a  great  deal  is  known 
about  the  human  body  in  health  and  in  disease,  and  as 
a  result  of  this  knowledge  human  life  has  been  pro- 
longed and  disease  is  not  so  terrible  as  it  once  was. 

3.  Cells.  —  Not  only  human  bodies,  but  the  bodies  of 
all  animals  and  the  substance  of  all  plants,  —  that  is,  all 
living  things,  —  are  made  up  of  very  minute  parts  called 
cells.     A  cell  is  usually  so  small  that  a  high  power  of 
the  microscope  is  necessary  to  see  it  at  all,  but  some  cells 
are   quite   large   and    can  be   seen  by  the    unaided    eye. 
Millions  upon  millions  of  these  tiny  things  are  required 
to  make  up  an  ordinary  human  body.     New  cells  grow 
from  old  cells,  and  in  this  way  the  body  increases  in  size. 
Cells  are  in  various  shapes.     Some  are  round,  some  flat, 
some  drawn  out  into  long  threads.     The  different  kinds 
of  cells  joined  together  in  different  ways  form  the  differ- 
ent kinds  of  tissue,  as  any  particular  part  of  the  body  is 
called.      Thus  we  have  bony  tissue,  which  is   hard  and 
solid ;  nerve  tissue,  which  is  soft ;  muscular  tissue,  which 
is  soft  and  in  threads  very  close  together ;  fibrous  tissue, 
which  is  firmer  and  very  tough  and  elastic. 

4.  Organs.  —  The  word  organ  as  used  in  Physiology 
means  any  part  of  the  body  that  does  a  special  kind  of 
work,  as  the  stomach  is  the  main  organ  of  digestion,  the 
heart  of  circulation,  and  so  on.     If  we  were  to  compare 
a  human  body  to  a  house,  we  might  say  that  the  materials, 
—  that  is,  the  stone,  brick,  wood,  sand,  glass,  iron,  etc.  — 


DRY  BONES.  6 

which  go  to  make  up  the  house  are  the  tissues,  while  the 
doors,  windows,  roof,  walls,  etc.,  are  the  organs  of  the 
house. 

5.  Systems. — When  several  organs  act   together  to 
perform  a  common  work,  we  speak  of  them  as  forming 
a  system.      Thus  all  parts  which  aid  in  preparing  the 
food  taken  together  form  the  digestive  system,  those  which 
circulate  the  blood  the    circulatory  system,   and  so   on. 
In  this  book  these  terms  will  not  be  frequently  used. 

6.  The  Composition  of  the  Body.  —  To  understand  ex- 
actly what  the  body  is  composed   of   would   require    a 
study  of  the  science  of  Chemistry.      Some  time  in  the 
future  you  will  study  this  science,  and  then  you  will  have 
a   better   understanding   of    Physiology.       Certain    facts 
must  at  first  be  learned,  although  we  may  not  understand 
them  thoroughly.     If  we  were  to  say  that  three-fourths 
of  the  human  body  was  water  you  would  scarcely  com- 
prehend it :  yet  such  is  a  scientific  fact.     Water  can  be 
so  combined  with  other  substances  that  its  identity  is 
lost,  and  it  is  only  by  careful  chemical  experiments  that 
it  can  be  separated  and  its  existence  proven. 


LESSON  2. 
Dry  Bones. 

i .  What  are  Bones  ?  —  Every  child  knows  something 
about  bones.  You  know  that  they  are  the  hard  parts  of 
the  higher  animals.  It  is  easy  to  see  that  they  are  the 
solid  framework  around  which  softer  and  more  yielding 
parts  are  built.  But  let  us  learn  a  little  more  about 


4  PHYSIOLOGY    FOE   BEGINNERS. 

bone  by  making  a  careful  examination  of  any  dry  bone 
we  may  chance  to  pick  up.     We  may  find  it  more  inter- 


FlG.    1. 


esting  than  we  at  first  might  suppose.     Strike  it  on  the 
table.     It  is  hard  and   solid.     Hit  it  with  a  hammer  a 


DRY   BONES.  5 

very  hard  blow.  It  breaks  more  easily  than  ordinary 
wood,  yet  perhaps  not  so  easily  as  a  piece  of  rock  of  the 
same  size  and  shape.  Try  to  break  it  with  your  hands. 
If  it  be  a  long,  slender  bone  you  will  perhaps  be  able  to  do 
it,  but  if  it  be  fresh  from  an  animal,  it  will  bend  before 
it  will  break.  It  has  a  certain  degree  of  brittleness  and 
yet  a  certain  degree  of  elasticity. 

2.  Structure  of  Bone.  — Examine  the  broken  fragment. 
If  it  be  of  a  long,  round  bone,  the  outside  will  be  seen  to 
be  of  a  solid  and  compact  nature  and  the  central  part 
a   cavity.      Near    the   enlarged    end,   you  will   observe 
that   it  is  full  of   small  holes,  or   cavities,  throughout, 
with  only  a  thin  shell  of  compact  bone  on  the  outside.     If 
it  be  a  flat  or  irregular  bone,  this  sponge-like  appearance 
will  be  in  the   center,  and  a  wall  of  compact  bone  on 
the  outside.     Make  a  collection  of  old,  dry  bones  of  any 
animal  or  animals,  and  break  some  of  them  in  different 
places,  and  compare  their   appearances.      Human   bones 
are  almost  exactly  similar  in  structure  to  the  bones  of 
domestic  animals. 

3.  Composition  of  Bone. — Put  a  bone  into  a  hot  fire 
and  leave  it  until  it  becomes  perfectly  white ;  when  cool, 
observe  that  it  has  lost  much  in  weight  but  yet  has  the 
same  bulk  and  shape,  and  the  appearance  is  the  same  ex- 
cept that  it  is  whiter.     Strike  it  gently  and  observe  that 
it  breaks  much  more  easily  than  one  that  has  not  been 
burned.     It  is  no  longer  tough  and  strong,  but  brittle  and 
fragile.     Something  has  been  removed  by  the  fire.     Now, 
if  you  put  a  bone  in  a  weak  acid  and  let  it  remain  several 
days,  and  examine  it,  you  will  find  that  it  has  lost  some  in 
weight  and  is  soft  enough  to  be  readily  bent  double  and 
even  tied  in  a  knot  if  long  enough,  but  otherwise  its  nat- 


6  PHYSIOLOGY    FOR    BEGINNERS. 

ure  and  appearance  are  the  same.     The  acid  has  removed 
something. 

The  fire  has  removed  the  gelatine,  or  animal  matter, 
which  gives  it  toughness  and  elasticity.  The  acid  has 
removed  the  mineral,  or  earthy,  matter,  which  gives  it 
firmness  and  solidity.  The  chemist  tells  us  that  about 
one-third  of  the  bone  is  gelatine  and  two-thirds  mineral 
matter. 

4.  Young  and  Old  Bones. —  The  bones  of  young  animals 
contain  in  proportion  more  of  the  soft  gelatine,  and  are 
therefore  more  easily  bent ;  while  the  bones  of  full-grown 
and  old  animals  contain  in  proportion  more  earthy  matter, 
and  are  therefore  more  solid  and  brittle.     Nature  arranges 
this  just  right.     The  young  animal  is  lighter  and  more 
active.     The  bones*  have  less  weight  to  bear  and  are  not 
so  liable  to  be  bent,  and  can  therefore  be  more  elastic,  thus 
permitting  greater  activity.     The  old  animal  is  heavier, 
and  the  bones  must  be  firmer  to  bear  the  weight.     It  is 
less  active  and  more  careful  in  its  movements,  and  the 
bones  are  less  liable  to  be  broken.  What  is  true  of  animals 
is  true  of  the  human  body.     It  would  not  do  for  children 
to  have  the  brittle  bones  of  old  people,  nor  for  old  people 
to  have  the  yielding  bones  of  children. 

5.  The  Marrow. —  The   long  bones  of   young  animals 
contain  a  reddish,  fatty-like  substance  in  their  center  we 
call  marrow.     It  consists  of  fat  and  blood  vessels.     In  old 
animals  this  marrow  is  yellow  and  consists  mostly  of  fat. 
In  the  young  and  growing  bone  it  helps  to  nourish  the 
bone  by  supplying  blood. 

6.  Bone  under  the  Microscope. —  It  is  to  be  hoped  your 
teacher,  or  some  one,  will  be  able  to  show  you  a  slice  of 
bone  under  the  microscope.     If  not,  the  picture  will  give 


DRY    BONES. 


FIG.  2. 


you  a  pretty  good  idea  of  how  it  appears  when  ground 
down  very  thin  and  highly  magnified.  By  comparing 
cross  and  longitudinal  sections  it  can  be  seen  that  numer- 
ous minute  channels  run  through  the  bone  in  various  di- 
rections. The  large,  whitish  spots  in  the  picture  are  these 
channels  cut  across.  These  are  called 
Haver sian  canals,  from  the  man  who 
first  discovered  them.  Numerous  dark 
spots,  with  dark  lines  running  in  all 
directions  from  them,  appear  arranged 
in  circles  around  the  canals.  These 
spots  are  the  cavities  of  bone  cells 
and  are  called  lacunce,  a  word  mean- 
ing "  little  lakes."  The  lines  are  little 
channels  branching  off  from  the  cells, 
and  are  called  canaliculi  ("little  ca- 
nals ").  In  the  living  bone  these  cavities  and  tubes 
are  filled  with  the  thin  part  of  the  blood,  which  brings 
the  material  for  the  growth  of  the  bone. 

7.  How  Bones  Grow. —  Bones  are  at  first  composed  of  a 
soft  substance  called  cartilage.  They  gradually  become 
harder  by  a  disappearance  of  the  cartilage  cells,  which  are 
replaced  by  bone  cells.  This  change  from  cartilage  to 
bone  is  very  gradual,  beginning  at  certain  points  in  a  bone 
and  increasing  all  around  these  points  until  nearly  the 
entire  bone  is  solidified.  This  is  not  completed  in  some 
bones  until  late  in  life.  Bones  also  increase  in  size  as  the 
animal  gets  larger.  When  bones  are  broken  in  a  healthy 
animal,  a  substance  pours  out  from  the  broken  ends,  and  if 
they  be  brought  together,  in  a  short  time  new  bone  will 
form  between  the  ends  and  firmly  join  the  pieces  into  one 
again. 


8  PHYSIOLOGY    FOR   BEGINNERS. 

8.  Coverings  of  Bones.  —  All  bones  are  covered  except 
at  their  ends  with  a  thin  membrane,  which  is  made  up 
mostly  of  small  blood  vessels.  From  this  membrane  the 
bone  gets  its  blood  for  its  nourishment.  If  you  get  a 
fresh  bone  from  a  young  animal,  you  may  be  able  to  peel 
off  this  membrane  with  the  aid  of  a  knife.  It  is  called 
the  per-i-os-te-um  (around  bone). 


LESSON  3. 
The  Uses  of  Bones. 

1.  The   Framework  of   the   Body. — Bones   form   the 
framework  around  and  within  which  the  softer  parts  are 
arranged  and  kept  in  position.     Without  the  bones  the 
body  would  be  a  shapeless  mass.     They  form  a  movable 
framework,  which  is  capable  of  being  folded  and  placed  in 
many  different  positions.     This  framework  is  called  the 
skel-e-ton  (hard). 

2.  They  Protect  the  Delicate  Parts.  —  The  brain  is  a 
soft,  delicate  mass  of  cells ;  the  lungs  are  a  fine  network 
of  soft  material ;  the  liver  is  a  mass  of  soft  cells ;  the  eye 
is  a  fine  piece  of  mechanism ;   the  ear  contains   minute 
bodies,  which  would  easily  be  destroyed  if  exposed.     All 
these  and  other  important  parts  are  surrounded  and  pro- 
tected ~by  bones. 

3.  They  Aid  Motion.  —  The  muscles  which  move  the 
parts  of  the  body  and  the  body  itself  from  place  to  place 
would  be  entirely  useless  without  the  bones,  which  form 
solid  points  of  attachment  for  them.     They  also  act  as 
levers  for  the  muscles. 


THE   BONES    OF    OUR   BODIES.  9 

4.  Bones  of  Animals  Useful  to  Man.  — Many  useful  and 
ornamental  articles  may  be  cut  from  bone.  When  ground 
to  a  fine  powder,  they  make  the  best  fertilizer  for  growing 
crops  the  farmer  can  use.  Phosphorus  and  other  chemi- 
cals used  in  the  arts  and  in  medicine  are  made  from 
bones.  Bone-black,  or  animal  charcoal,  which  is  used  for 
making  shoe-blacking,  for  painting,  and  to  purify  sugar, 
is  made  from  bones. 


LESSON  4. 
The  Bones  of  Our  Bodies. 

[NOTE.  —  The  teacher  should  not  require  pupils  to  memorize  the  names  of  the 
bones,  but  by  frequent  reference  to  them  most  of  them  will  be  learned.] 

1.  Number  of  Bones. — There  are  two  hundred  bones 
in  a  human  body.     This  does  not  include  the  teeth,  which 
are  not  properly  called  bones,  nor  the  very  minute  bones 
in  the  internal  ear.     Imagine  a  line  to  pass  through  the 
body  from  the  crown  of  the  head  to  a  point  between  the 
feet.     Nearly  in  this  line  will  be  found  thirty-four  single 
bones.     The  remaining  one  hundred  and  sixty-six  bones 
are  arranged  in  pairs,  one  on  each  side  of  the  body. 

2.  The  Names  of  the  Bones.  —  Not  only  has  every  bone 
in  the  body  a  name,  but  all  the  principal  grooves  and  pro- 
jections and  openings  in  each  bone  have  names.    These 
names  are  from  the  Latin  and  Greek  languages,  and  were 
given  to  the  bones  when  these  languages  were  the  prin- 
cipal ones  used  by  scholars.     They  may  sound  foreign  to 
us  at  first,  but  you  can  soon  become  familiar  with  many 
of  them. 


10 


PHYSIOLOGY    FOR   BEGINNERS. 


3.  The  Bones  of  the  Head.  —  There  are  twenty-two 
bones  in  the  head.  All  taken  together  form  the  skull. 
The  skull  is  composed  of  the  cra-ni-um,  or  that  part  that 


FIG.  3. 


encloses  the  brain,  and  the  face.  There  are  eight  bones  in 
the  cranium,  firmly  joined  so  as  to  form  a  box  in  which 
the  brain  lies  perfectly  protected  from  injury. 

Here  are  the  names  of  the  bones  of  the  cranium :  — 


THE  BONES  OF  OUR  BODIES.  11 

The  Frontal  (front) :  forms  the  forehead. 
The  Oc-cip-i-tal  (back  of  head)  :  forms  back  and  lower 
part. 

The  Sphe-noid  (wedge-like) :  forms  the  base. 

The  Eth-moid  (sieve-like)  :  between  eye  cavities. 

Two  Tem-po-ral :  one  on  each  side  below. 

Two  Pa-ri-e-tal  (a  wall)  :  one  on  each  side  above. 

There  are  fourteen  bones  in  the  face  :  — 

Two  Na-sal  (nose) :  form  the  "  bridge  "  of  the  nose. 

Two  Ma-lar  (cheek)  :  below  eye  cavities. 

Two  Lach-ry-mal  (a  tear) :  inner  corner  of  eye  cavities. 

Two  Pal-ate  :  form  back  part  of  roof  of  mouth. 

Two  Inferior  tur-bi-nated  (scroll-like) :  in  nose  cavities. 

Two  Superior  max-il-la-ry  (jaw  bone) :  the  upper  jaw. 

Vo-mer  (plow-share)  :  between  nose  cavities. 

Inferior  max-il-la-ry :  the  lower  jaw. 

4.  Bones  of  the  Trunk,  or  Body  Proper.  —  There  are 
fifty-eight  bones  in  the  trunk,  forming  three  groups : 
the  thorax,  or  chest ;  the  spinal  column,  or  backbone  ;  and 
the  pelvis,  or  hips. 

There  are  twelve  pairs  of  ribs.  The  upper  or  first  seven 
pairs  are  joined  to  the  sternum  in  front  by  separate  short 
pieces  of  cartilage  and  are  called  the  true  ribs.  The  other 
five  pairs  are  called  false  ribs.  The  two  last  pairs  are  not 
joined  to  the  sternum  and  are  called  floating  ribs.  The 
other  three  pairs  have  their  cartilages  united  to  each  other, 
and  the  upper  one  to  the  seventh  rib.  All  are  joined  to 
the  spinal  column. 

The  Ster-num  (hard),  or  breastbone. 

Two  Clav-i-cles  (key),  or  collar-bones. 

Two  Scap-u-las  (spade),  or  shoulder-blades. 

The  ribs,  sternum,  clavicles,  and  scapulas  together  form 


12 


PHYSIOLOGY    FOR    BEGINNERS. 


the  thorax,  which  is  a  kind  of  cage,  enclosing  and  protect- 
ing the  heart,  lungs,  and  other  organs. 

The  spinal  column  is  a  column  of  twenty-four  bones, 
called  ver-te-brae  (singular  ver-te-bra,  that  which  turns). 
Each  vertebra  is  a  round  mass  of  bone  with 
projections,  some  of  which  form  a  ring ;  and 
when  all  are  together  these  rings  form  a  chan- 
nel called  the  spinal  canal.  In  this  channel 
lies,  perfectly  protected,  the  spinal  cord,  an 
important  part  of  the  nervous  system.  The 
first  or  upper  vertebra  is  called  the  at-las, 
from  the  name  of  a  heathen  god,  who  was 
supposed  to  support  the  earth  on  his  shoulders. 
The  second  is  called  the  ax-is,  or  pivot.  When 
you  move  the  head  up  and  down,  as  in  bow- 
ing, the  occipital  bone  of  the  head  glides  on 
the  atlas.  When  you  turn  your  head  from 
side  to  side,  the  atlas  turns  around  the  axis. 

The  first  seven  vertebrae  are  called  cer-vi- 
cal  (of  the  neck).  The  next  twelve  are  called 
dor-sal  (of  the  back),  and  the  last  five  are 
called  lum-bar  (of  the  loins). 

The  pel-vis  (a  basin)  is  formed  by  the  two 
in-nom-i-na-ta  (nameless)  bones  ;  the  sa-crum 
(sacred)  bone,  which  is  really  a  continuation 
of    the     spinal     column ;     and    the    coc-cyx 
FIG.  4.        (cuckoo),  a  small  bone  attached  to    the   end 

of  the  sacrum. 

The  os  hy-oi-des  (u-shaped)  is  a  small  bone  at  the  root 
of  the  tongue,  having  many  muscles  attached  to  it. 

5.    The  Bones  of  the  Upper  Limbs.  —  Each  upper  limb 
contains  thirty  bones  : 


THE  BONES  OF  OUR  BODIES. 


13 


bones  of  the  forearm. 


The  hu-me-rus  (arm) :  the  long  bone  of  the  upper  arm. 
The  ul-na:  1 
The  ra-di-us :  j 
The  car- pus  (wrist) :  eight  small  bones  arranged  in  two 
rows. 

Beginning  with  the  side  the  thumb  is  on  the  bones  of  the  upper 
or  row  next  the  arm  are  as  follows  :  scaph-oid  (boat-shaped) ; 
sem-i-lu-nar  (half  moon) ;  cu-ne-i-form  (wedge-shaped) ;  pi-si- 
form  (pea-shaped).  Beginning  next  the  thumb,  in  the  second  or 
row  next  the  hand  they  are :  tra-pe-zi-um ;  trap-e-zoid ;  os  mag- 
num (large  bone);  un-ci-form  (hook  like). 

The  met-a-car-pus  (beyond  the  carpus),  or  bones  of  the 
hand,  five  in  number. 


FIG.  5. 

The  pha-lan-ges  (rows  of  soldiers),  fourteen  in  number, 
three  to  each  finger  and  two  to  the  thumb. 

6.  Bones  of  the  Lower  Limbs.  — Each  lower  limb  has 
thirty  bones : 

The  fe-mur  (thigh) :  the  bone  of  the  thigh,  or  upper 
leg,  the  longest  and  heaviest  bone  in  the  body. 

The  tib-i-a  (flute) :  the  large  bone  of  the  leg  proper, 
the  "  shin  bone." 


14  PHYSIOLOGY    FOR    BEGINNERS. 

The  fib-u-la  (a  brace) :  the  small  bone  of  the  leg. 
The  pa-tel-la  (a  small  pan) :  the  knee  cap. 
The  tar-sus  (ankle)  :  seven  small  bones. 

The  largest  is  the  os  cal-cis,  or  heel  bone ;  the  as-trag-a-lus 
(a  die)  joins  the  ankle  to  the  leg;  the  cu-boid  (cube-shaped);  the 
scaph-oid ;  the  internal,  middle,  and  external  cu-ne-i-form. 

The  met-a-tar-sus  (beyond  the  tarsus),  or  bones  of  the 
foot,  five  in  number. 

The  pha-lan-ges  correspond  to  the  phalanges  of  the 
hand. 


LESSON  5. 
How  to  Care  for  Our  Bones. 

1.  Our  Bones  are  Alive.  — Although  the  bones  we  have 
been  experimenting  with   are   simply   dead   matter,  like 
sticks  and  stones,  we  must  bear  in  mind  that  the  bones 
in  our  bodies  are  living  things.      The  blood   circulates 
through  them,  and  they  are  being  torn  down  and  rebuilt, 
as  all  other  tissues  of  the  body  are.     Constant  pressure  on 
a  bone  will  cause  it  to  grow  crooked,  just  as  a  young  tree 
may  be  made  to  grow  crooked  by  binding  it  to  a  stake.     The 
weight  of  the  body  tends  to  bend  the  bones  in  young  children, 
and  by  walking  too  soon  they  frequently  become  bow-legged. 

2.  Bones  Need  Nourishment. — We  shall  learn  after  a 
while  that  the  body  is  kept  in  a  proper  state  by  the  nourish- 
ment afforded  by  the  blood,  and  the  blood  gets  its  nourish- 
ment from  the  food  we  eat.     The  bones  require  a  constant 
supply  of  nourishment   suitable  to  their  nature.     Good 
food  in  proper  quantities,  and  all  the  conditions  which  favor 
proper  digestion  of  the  food,  and  circulation  of  the  blood 


HOW  TO  CARE  FOR  OUR  BONES.          15 

are  necessary  to  have  healthy  and  perfect  bones.  Alcoholic 
drinks  disturb  the  digestion  and  tend  to  diminish  the  nour- 
ishing qualities  of  the  blood)  and  therefore  indirectly  affect 
the  growth  and  condition  of  bones.  Some  professional  beg- 
gars are  so  cruel  as  to  give  their  children  whiskey  or  gin, 
to  stunt  their  growth  and  make  them  puny  and  sickly- 
looking,  that  they  may  excite  the  compassion  of  those 
from  whom  they  beg.  This  illustrates  the  effect  of  alcohol 
on  the  bones. 

3.  Tight  Clothing. —  The  Chinese  much   admire  small 
feet  in  women,  and  sometimes  the  parents  bind  the  feet 
of  their  children  when  very  young  so  that  they  cannot 
grow.     A  horrible  deformity  is  produced,  sometimes  so 
great  that  the  person  is  unable  to  walk.     Our  fashionable 
people  frequently  deform  their  feet  by  crowding   them 
into  shoes  too  small  for  them.     School  girls  often  fool- 
ishly try  to  produce  a  small  waist  by  wearing  a  tightly 
laced  corset.     The  ribs  are  made  to  grow  inward,  and  the 
organs  within  the    chest    are  crowded  for   room.     Much 
suffering  later  in  life  is  the  consequence  of  such  absurd  con- 
duct.    Clothing  should  never  be  tight.     The  bones  should 
have  freedom  to  grow  in  a  natural  way. 

4.  Unnatural  Positions. —  Pupils  in  school  often  acquire 
habits  of  leaning  or  bending  over  their  desks  until  there 
is  actual  deformity  in  the  shoulders  and  spinal  column. 
Round,  or  stoop,  shoulders   are  always  caused  ~by  careless 
habits.     Always  sit  or  stand  erect,  taking  care  to  keep  the 
shoulders  back. 

5.  Old  persons  are  more  liable  to  have  broken  bones,  as 
their  bones  are  more  brittle  ;  therefore  they  should  be  care- 
ful to  avoid  all  causes  of  falling.     Children  should  not  be 


16  PHYSIOLOGY   FOK    BEGINNERS. 

lifted  by  the  arms,  nor  placed  on  their  feet  too  soon  before 
they  are  able  to  walk.     Their  bones  are  easily  bent. 

6.  Fresh  air,  sunshine,  cleanliness,  wholesome  food  and 
drink,  exercise,  and  avoidance  of  exposure  to  extreme  cold  and 
to  dampness,  are  all  necessary  for  a  perfectly  healthy  condi- 
tion of  the  ~bony  framework. 


LESSON  6. 
The  Joints. 

1.  The  Perfect  Machine. —  The  human  body   is   like  a 
perfect  piece  of  machinery.     There  is  a  good  reason  for 
having  so  many  bones,  or  pieces,  in  the  skeleton.    This  gives 
a  great  variety  of  motions.     Observe  how  many  positions 
the  hand  and  fingers  are  capable  of  taking,  and  how  many 
kinds  of  motions  may  be  made  with  them.     This  would 
not  be  possible  if  the  framework  were  not  in  so  many 
pieces.     The  body  is  not  only  perfectly  adapted  to  many 
motions  and  positions,  but  it  is  a  very  strong  machine,  not 
easily  put  out  of  repair  by  use.     The  numerous  pieces  of 
the  skeleton  are  firmly  and  perfectly  joined  together,  in 
some  places  permitting  much  motion,  in  others  very  little, 
according  as  the  necessity  exists. 

2.  Parts  of  a  Joint.  —  To  form  a  movable  joint,  the 
following  parts  are  necessary :  the  edges  or  ends  of  two 
bones,  ligaments,  cartilage,  synovial  membrane,  and  synovia. 

3.  Ligaments.  —  These  are  bands  or  cords  of  fibrous 
tissue,  elastic,  pliable,  and  very  tough,  which  bind  the  ends 
of  the  bones  together  in  a  manner  similar  to  strap  hinges 
on  a  door.     Some  pass  from  one  bone  to  another  across  the 


THE    JOINTS.  17 

joint,  others  completely  surround  the  joint  as  with  a  cap. 
You  may  readily  point  out  the  ligaments  in  a  joint  from 
the  leg  of  an  ox  or  sheep,  as  you  find  it  in  the  butcher's 
shop.  Try  cutting  one  with  a  knife,  and  observe  how 
very  tough  they  are.  Try  to  pull  a  joint  apart ;  you  can- 
not do  it,  so  strong  are  the  ligaments  which  hold  it 
together.  Ligaments  are  not  well  supplied  with  blood, 
and  when  stretched  or  partly  torn,  as  in  a  sprained  ankle, 
they  are  a  long  time  in  healing.  One  should  be  careful  in 
jumping  over  fences,  running  on  uneven  ground,  and  in 
play,  lest  a  sprained  ankle  be  the  result. 

4.  Cartilage.  —  In  all  movable  joints  the  ends  of  the 
two  bones  are  covered  with  a  thin  layer  of  a  pearly  white 
substance,  very  smooth  and  firm,  yet  much  softer  than 
bone.     This  is  permanent  cartilage,  that  is,  cartilage  that 
never  changes  to  bone.     It  acts  as  a  cushion  to  lessen  the 
jar  or  shock  that  would  occur  in  walking,  running,  or  leap- 
ing.    Between  the  vertebrae  there  is  a  separate  piece  of 
fibro-cartilage  (a  kind  containing  fibers).     The  weight  of 
the  body  during  the  day  compresses  these  cartilages  ;  and 
at  night,  when   lying  down,  they   regain  their    original 
condition.     A  little  flattening  of  each  of  these  cartilages 
amounts  to  nearly  half  an  inch  in  all  of  them,  so  that  a 
man  is  really  half  an  inch  taller  in  the  morning  than  he  is 
in  the  evening.     These  cartilages  in  the  backbone  permit 
a  considerable  bending  of  the   spinal   column,  each  one 
yielding  just  a  little. 

5.  A  Joint  is  Self-oiling.  — In  all  machinery,  wherever 
one  part  slides  or  moves  on  another  there  would  be  much 
wear,  and  more  power  would  be  required  to  move   the 
parts,  if   they  were  not  frequently  oiled.     In  the    body 
nature  has  provided  for  this  by  a  beautiful  contrivance. 


18  PHYSIOLOGY    FOR   BEGINNERS. 

A  membrane  covers  each  movable  joint  inside  of  the  1: 
aments.  This  membrane  secretes,  that  is  manufactures, 
and  pours  out  a  slippery,  transparent  fluid,  called  syn-o-vi-a, 
or  "  joint-water."  This  keeps  the  parts  always  moist  and 
prevents  friction.  The  membrane  is  called  the  synovial 
membrane.  If  it  be  cut  or  punctured,  the  joint-water  runs 
out,  and  the  joint  is  stiff  until  it  heals  up  and  is  resupplied. 
A  disease  of  the  membrane  may  produce  permanent  stiff- 
ness of  the  joint. 

6.  Kinds  of  Joints.  —  There  are  many  kinds  of  joints, 
some  permitting  much  motion  in  all  directions,  others 
scarcely  any  motion  at  all.  The  most  freely  movable 
joints  are  in  the  limbs,  where  the  greatest  motion  is  needed. 
The  hip  joint  is  called  a  ball-and-socket  joint,  because  the 
end  of  the  femur  is  rounded,  like  a  ball,  and  fits  perfectly 
into  a  cup-like  cavity  or  socket  in  the  innominata  bone. 
This  permits  motion  in  all  directions.  The  shoulder 
joint  is  similar,  but  the  cavity  is  not  so  deep,  which  permits 
still  greater  freedom  of  motion.  The  knee,  ankle,  and 
elbow  are  hinge  joints,  permitting  motion  in  two  directions 
only,  back  and  forth. 


LESSON  7. 
The  Muscles. 

i.  What  are  Muscles?  —  They  are  the  lean  meat,  or 
flesh,  of  an  animal.  They  give  the  general  form  to  the 
body  and  make  up  the  greater  part  of  its  weight.  All  the 
motions  of  the  body  are  produced  by  the  contractions  of 
these  bundles  of  fibers  we  call  muscles.  They  are  found 


THE    MUSCLES. 


19 


109 


FIG.  6. 


20  PHYSIOLOGY    FOR   BEGINNERS. 

in  the  skin  and  cause  it  to  draw  up  into  little  lumps  when 
our  bodies  are  chilled,  producing  what  is  often  called 
"  goose-flesh."  They  are  found  in  the  stomach  and  intes- 
tines, and  their  contraction  causes  the  food  to  move  along 
during  digestion.  Swallowing  is  produced  by  muscles. 
The  various  changes  in  the  voice  are  caused  by  minute 
muscles  in  the  throat.  We  exercise  a  tiny  muscle  in  the 
ear  when  we  listen  to  sounds,  and  one  in  the  eye  when  we 
look  at  near  objects.  The  heart  is  one  large  muscle.  The 
bones  are  concealed  nearly  everywhere  by  muscles,  which 
in  contracting  produce  all  their  motions.  Thus,  you  see, 
muscles  are  important  parts  of  the  body. 

2.  Sizes  and  Shapes  of  Muscles. — The  longest  muscle 
hi  the  body  extends  from  the  hip  bone  to  the  tibia,  about 
two  feet  in  length.     The  shortest  is  in  the  middle  ear  and 
is  only  a  small  fraction  of  an  inch  long.     There  are  all 
sizes  between  these  two  extremes.     The   most  common 
shape  is  spindle-shaped  (thick  in  the  middle  and  tapering 
to  each  end).     Some  are  fan-shaped,  others  like  a  feather, 
the  fibers  running  out  from  a  central  line.     A  few  are 
circular,  and  when  they  contract  they  dimmish  or  close 
the  opening  they  surround.     There  is  one  such  around 
the  mouth  and  another  around  the  eye. 

3.  Number  and  Names  of  Muscles.  —  Most  of  the  mus- 
cles are  in  pairs,  one  on  each  side  of  the  body.     There  are 
about  five  hundred  distinct  muscles  in  the  body,  having 
special  names,  beside  a  great  many  sets  of  muscular  fibers, 
which  have  no  special  name.     The  names,  like  those  of 
the  bones,  are  all  in  Latin  or  Greek  and  have  each  a 
significance.      Thus    some   are  named  from  their  shape 
resembling  some  object,  others  from  their  location  near  or 
upon  some  bone,  others  again  from  their  action  or  use. 


THE    MUSCLES.  21 

4.  The  Tendons,  or  Sinews.  —  As  muscles  are  the  movers 
of  the  body,  they  must  in  some  way  be  fastened  to  bones 
and  other  parts.     Sometimes  they  are  attached  directly  to 
the  bones,  but  usually  by  strong,  fibrous  cords  or  bands 
called    tendons.     In   some   cases   the   tendons  are   much 
longer   than   the   muscles.      When   you    close   your   fist 
tightly,  you  will  observe  cords  standing  out  under  the 
skin  of  the  wrist.     These  are  the  tendons  of  the  muscles 
which  move  the  fingers.      Muscles  are  in  some  cases  at- 
tached to  cartilages,  to  ligaments,  to  the  skin,  and  to  other 
muscles.     The  large  tendon,  which  is  attached  to  the  heel 
bone,  and  which  can  be  felt  behind  the  ankle,  is  called  the 
Tendon  of  Achilles.     It  was  so  named  because,   as  the 
story  goes,  Achilles,  the  Greek  warrior,  was  dipped  by  his 
mother  in  the  river  Styx,  and  thus  made  incapable  of 
being  injured.     But  she  held  him  by  the  heel  and  this 
part  did  not  get  dipped,  and  it  so  happened  that  he  was 
wounded  in  this  part  and  died  from  the  effects  of  the 
wound.     This  tendon  is  sometimes  too  short,  and  the  heel 
is  drawn  up,  causing  the  deformity  known  as  "  club-foot." 
It  can  frequently  be  cured  by  a  surgical  operation  which 
consists  of  simply  cutting  the  tendon  beneath  the  skin,  in 
which  case  the  space  fills  up  and  the  tendon  becomes 
lengthened.     Children    with    deformed   limbs    should   be 
examined  by  competent  surgeons,  as  in  many  cases  they 
may  be  cured  by  simple  operations. 

5.  Structure  of  Muscles.  —  Take  a  piece  of  boiled  meat 
and  examine  it.     You  observe  that  it  seems  to  be  made  up 
of  fibers,  or  threads,  lying  side  by  side  and  in  small  bun- 
dles.    You  may  strip  off  these  fibers.     Maybe  you  will  get 
a  dozen  or  more  of  them,  appearing  as  one  thread ;  but  by 
careful  picking  you  will  finally  split  it  up,  until  you  have 


22  PHYSIOLOGY   FOR   BEGINNERS. 

a  thread  finer  than  the  finest  hair,  which  you  cannot 
further  divide.  This  is  called  the  ultimate  fiber.  The 
whole  muscle  is  made  up  of  these  small  threads,  which 
seem  to  be  held  together  by  a  fine,  cobweb-like  tissue. 
This  tissue  is  called  the  per-i-mys-i-um  (around  muscle). 
It  also  forms  a  sheath,  or  coat,  for  the  entire  muscle. 

6.  Muscle  Fibers  under  the  Microscope.  —  If  we  place  a 
single  fiber  under  a  microscope  of  high  power,  we  see 
many  dark  lines  running  across  the  fiber  and  lengthwise, 
dividing  it  up  into  little  blocks,  or  squares.  These  lines 
have  been  counted  and  there  are  as  many  as  ten  thousand 
in  an  inch.  Each  little  block,  or  square,  is  supposed  to  be 
a  muscle  cell,  yet  this  subject  is  not  yet  well  understood. 
Muscles  which  have  this  appearance  under  the  microscope 
are  called  striped  muscles  ;  and  all  such,  except  the  heart, 
contract  in  obedience  to  the  will  and  are  said  to  be  volun- 
tary muscles.  The  muscles  of  the  digestive  organs  and 
some  others  are  purely  involuntary  and  have  a  different 
appearance  when  magnified.  They  are  made  up  of  flat, 
tapering  bands,  interlaced  in  all  directions,  and  are  called 
unstriped  muscles. 


LESSON  8. 
The  Uses  of  Muscles. 

i.  How  Muscles  Act.  — Muscles  move  the  parts  they  are 
attached  to  by  contracting,  that  is,  they  grow  shorter  and 
thicker,  and  thus  pull  upon  the  parts  fastened  to  their 
ends.  Muscles  contract  in  obedience  to  the  will,  the  power 
to  make  them  contract  being  sent  along  a  nerve,  which  is 
connected  with  the  brain.  But  in  an  animal  just  killed 


THE    USES    OF    MUSCLES.  23 

they  can  be  made  to  contract  by  touching  the  nerve  which 
goes  to  them,  by  striking  the  muscles  themselves,  or  by 
applying  electricity  or  an  acid  to  them.  In  frogs,  snakes, 
and  turtles,  the  muscles  may  be  made  to  contract  and  the 
limbs  to  move  hours  after  the  animal  is  dead,  in  the  turtle 
even  after  the  lapse  of  four  days  or  more.  When  a 
chicken's  head  is  cut  off  with  one  blow  of  the  axe,  the  irri- 
tation of  the  air  upon  the  ends  of  the  severed  nerves  causes 
its  muscles  to  contract,  and  the  animal  jumps  about  in  a 
lively  manner,  although  it  is  dead  and  ceases  to  suffer 
the  moment  its  head  is  cut  off. 

2.  The  Instruments  of  Motion. — As  we  have  said,  all 
motion  in  the  body  is  produced  by  muscular  contraction. 
There  is  one  exception  to  this  in  the  case  of  cilia,  which 
will  be  described  under  the  breathing  organs.     How  im- 
portant the    power  of   motion  is  to    an   animal   we  can 
readily  see.     By  contraction  of  muscles  it  is  enabled  to 
move  from  place  to  place  and  seek  its  food,  also  to  seize 
its  food  and  to  carry  itself  away  from  danger.     Even  after 
the  food   is   conveyed  to  the    stomach,  muscular   action 
carries  it  to  all  parts  of  the  body ;  for  the  food  becomes  a 
part  of  the  blood,  and  muscular  contraction  of  the  heart 
and  blood  vessels  sends  the  blood  to  every  part. 

3.  Language  Depends  on  Muscular  Action.  —  The  most 
universal  language  is  that  of  signs  and  gestures  made  by 
the  limbs.     But  all  articulate  language,  or  speech,  is  the 
result  of  muscular  action.     The  human  voice  is  capable 
of  an  almost  infinite  variety  of  sounds,  and  each  is  pro- 
duced by  variations  in  muscular  contraction.     The  mus- 
cles of  the  face  are  capable  of  expressing  a  great  variety 
of  feeling,  as  of  joy,  sorrow,  anger,  fear,  etc. 


24  PHYSIOLOGY    FOR    BEGINNERS. 

4.  The  Strength  of  Muscles.  —  A  muscle  is  a  soft,  yield- 
ing mass  easily  torn  apart ;  yet,  strange  to  say,  a  muscle 
contracting  in  obedience  to  the  will  can  exert  enormous 
force.     One  man  lifted  1442 i  pounds  by  his  hands  alone, 
and  another,  by  means  of  harness  attached  to  his  body  so 
that  he  could  bring  many  muscles  into  action,  lifted  3239 
pounds.     We  cannot  understand  this  mysterious  power, 
how  such  a  weak  thing  can  draw  itself  together  and  exert 
such  enormous  force.     It  is  an  evidence  of  the  wisdom  and 
power  of  the  Great  Contriver  of  the  Universe.     The  work 
of  the  world,  —  the  building  of  towns  and  cities,  railroads 
and  ships,  the  removal  of  the  forests  and  the  cultivation 
of  the  soil,  the  production  of  manufactured  articles,  the 
mining,  the  commerce,  and  even  the  education  and  moral 
improvement  of  mankind,  —  is,  at  the  foundation,  a  result 
of   muscular  activity,  guided  and  controlled  by  another 
force,  mind  activity. 

5.  The  beauty  of  the  human  form  depends  largely  upon 
muscular  development.     It  is  true  that  the  roundness  and 
plumpness  of  form  is  due  largely  to  the  fat  which  fills  out 
the  spaces  not  occupied  by  muscles,  yet  the  graceful  taper- 
ing of  limbs  and  the  beauty  of  expression  depend  on  the 
full  development  of  muscles. 


LESSON  9. 
The  Care  of  Muscles. 

i.  Exercise. — If  muscles  are  not  exercised,  they  be- 
come weak  and  small.  Yet  too  much  exercise  is  not  good 
for  them.  No  muscle  can  work  constantlv.  It  must  have 


THE    CARE    OF    MUSCLES.  25 

rest.  The  heart  appears  to  be  in  constant  motion,  yet  it 
is  not.  It  contracts,  and  then  there  is  a  pause.  If  you 
were  to  add  together  the  brief  periods  in  which  the  mus- 
cle fibers  of  the  heart  are  not  acting,  it  would  amount  to 
as  much  as  nine  hours  out  of  every  twenty-four.  A  mus- 
cle may  contract  many  times  in  succession  without  injury, 
but  it  cannot  remain  in  a  state  of  contraction  very  long 
without  injury.  To  hold  your  arm  out  straight  from  the 
body  requires  the  steady  contraction  of  several  muscles. 
Did  you  ever  try  to  see  how  long  you  could  hold  it  out  ? 
It  very  soon  becomes  painful.  It  is  much  easier  to  push 
it  out  and  draw  it  back  in  rapid  succession  for  several 
minutes  than  to  keep  it  held  out  for  the  same  length  of 
time.  When  you  push  it  out  and  draw  it  back,  you  allow 
one  set  of  muscles  to  rest  while  the  other  set  works.  So 
in  walking  and  in  performing  almost  any  kind  of  labor, 
muscles  alternate  with  each  other  in  resting  and  working. 

2.  Rest.  —  Rest  is  as  important  as  exercise.  The  great 
secret  of  caring  for  our  muscles  consists  in  a  proper  alter- 
nation of  exercise  and  rest  for  all  the  muscles  in  the  body. 
This  is  not  always  easy  to  determine.  When  we  have  ex- 
ercised a  muscle  too  long,  we  feel  tired.  This  is  nature's 
warning  that  we  must  give  the  part  a  rest.  But  fre- 
quently our  minds  are  engaged  in  thought,  bent  on  accom- 
plishing some  work,  and  we  do  not  regard  the  feeling 
of  weariness,  and  thus  overwork  our  muscles.  Proper 
rest  is  not  complete  idleness.  We  may  rest  one  part 
while  another  works.  It  requires  one  set  of  muscles  to 
keep  the  body  in  a  standing  position  and  different  muscles 
are  brought  into  use  in  sitting ;  and  even  in  standing  and 
sitting  in  different  positions  different  muscles  are  used. 
It  is  really  easier  to  walk  for  an  hour  than  to  stand  per- 


26  PHYSIOLOGY    FOR   BEGINNERS. 

fectly  still  for  an  hour,  because  in  standing  certain  muscles 
must  be  kept  in  a  state  of  contraction  to  keep  the  body 
upright,  while  in  walking  one  set  of  muscles  rest  while 
another  set  is  working.  However,  a  slight  shifting  of 
position  in  standing  will  change  the  muscles  and  give 
them  a  partial  rest. 

3.  Avoid  Violent   Exercise.  —  By  rapid  and  powerful 
contraction  muscles  may  be  strained  and  injured.     Run- 
ning and  leaping  are  not  very  likely  to  injure  children, 
because  their  bodies  are  light  and  the  muscular  effort  not 
very  great ;  yet  in  the  effort  to  outrun  or  outleap  a  rival 
one  may  strain  the  muscles.     Lifting  heavy  weights  often 
results  in  strain  of  the  muscles.     Long  continued  exercise, 
as  in  jumping  a  rope,  may  so  excite  the  action  of  the  heart 
as  to  cause  its  sudden  paralysis,  or  it  may  result  in  the 
bursting   of  a   blood  vessel.     Such   cases   have   occurred 
within  the  author's  knowledge.     Girls,  in  trying  to   see 
who  could  jump  a  rope  the  greatest  number  of  times  in 
succession,  have  suddenly  dropped  dead  from  failure  of 
the  heart  or  bursting  of  a  blood  vessel. 

4.  Other  Parts  Benefited  by  Exercise.  —  When  the  en- 
tire body  is    exercised,  as  in  walking  and  running,  the 
heart  beats  more  rapidly  and  we  breathe  faster,  and  thus 
more  blood  is  sent  to  every  part  of  the  body,  and  the  im- 
purities are  more  rapidly  thrown  off  through  the  lungs. 
The  perspiration  is  also  increased,  and  thus  impurities  are 
thrown  out.     When  not  overdone,  this  is  very  beneficial 
to  all  parts,  including  the  muscles  themselves,  as  they 
receive  more  nourishment  from  a  better  circulation  and 
purification  of  the  blood.     The  power  of  digestion  and 
the  action  of  the  liver  and  other  glands  are  also  increased 
by  muscular  exercise.     The  nervous  system  is  also  bene- 


THE    CARE    OF    MUSCLES.  27 

fited,  and  the  mind  made  clearer  by  proper  exercise  of 
the  muscular  system.  You  can  always  study  better  after 
a  proper  amount  of  exercise. 

5.  Kinds  of  Exercise  to  be  Recommended. — The  per- 
son's  occupation    in   some   cases    gives   him   the  proper 
amount  and  variety  of  exercise.     The  farmer  and  many 
mechanics  usually  get  enough  exercise  in  their  daily  oc- 
cupations.    They  need  guard  only  against  overwork  and 
straining  their  muscles.     But  persons  whose  occupation 
requires  a  sitting  posture,  and  those  whose  work  is  mental 
rather  than   physical,    should   take   exercise  which  will 
bring  into  use  those  muscles  that  are  not  used  in  the 
ordinary  work. 

Walking  is  good  exercise  for  nearly  all  people.  It 
brings  into  use  a  large  number  of  muscles.  Horseback 
riding  is  largely  a  passive  kind  of  exercise,  benefiting 
organs  by  the  gentle  shaking  it  gives  them.  It  is  useful 
to  persons  who  are  not  strong.  Carriage  riding  gives  but 
little  exercise,  but  for  invalids  and  very  delicate  persons 
it  is  good.  Out-door  games  are  valuable,  but  in  some,  as 
base-ball  and  foot-ball,  there  is  danger  of  making  the 
exercise  too  violent.  Gymnastic  exercises,  such  as  swing- 
ing clubs,  dumb-bells,  climbing  and  pulling  on  ropes,  poles,, 
etc.,  are  useful  when  out-door  exercise  cannot  be  taken. 
There  should  always  be  a  careful  gradation  in  these  exer- 
cises, as  they  may  easily  be  overdone. 

6.  Best  Time  for  Exercise. — The  morning  is  generally 
the  best  time  for  exercise.     The  body  has  been  resting 
during  the  night  and  can  endure  the  exercise  better.    Per- 
sons who  find  themselves  troubled  with  sleeplessness  are 
often  benefited  by  gentle   exercise  just  before  retiring. 
Only  the  most  gentle  exercise  should  be  taken  immedi- 


28  PHYSIOLOGY    FOR    BEGINNERS. 

ately  before  and  after  meals.     The  stomach  requires  the 
energies  of  the  body  at  that  time. 

Exercise  should  be  of  a  kind  pleasurable  in  itself. 
When  we  are  not  conscious  that  we  are  exercising,  it 
does  us  the  most  good.  To  take  a  walk  merely  as  a  task 
to  be  performed  will  not  benefit  us  as  much  as  to  go  out 
to  gather  flowers,  insects,  or  shells.  Every  one  should 
take  an  interest  in  some  subject  that  would  require  excur- 
sions to  the  fields  and  woods,  or  be  interested  in  the  use 
of  tools  as  a  pastime  for  leisure  hours. 

7.  Effects  of  Alcohol  on  the  Muscles.  —  It  was  once 
thought  that  alcohol  increased  a  man's  strength,  and  it 
was  the  custom  to  serve  out  whiskey  or  some  other  alco- 
holic drink  to  "harvest  hands";  but  this  is  a  mistake. 
Alcohol  only  apparently  increases  strength.  It  stimulates 
us  to  use  all  the  strength  we  have.  It  is  like  a  whip  to 
a  horse,  making  him  exert  his  strength  but  adding  noth- 
ing to  his  power.  A  drunken  man  staggers,  and  his  voice 
is  thick  and  husky.  Sometimes  he  sees  double  and  im- 
agines other  persons  are  staggering.  This  is  because  the 
alcohol  so  affects  his  brain  as  to  destroy  its  control  over 
the  muscles.  He  staggers,  because  he  cannot  make  one 
leg  move  in  harmony  with  the  other.  The  muscles  of  his 
tongue  do  not  act  properly,  and  he  cannot  articulate  cor- 
rectly. He  cannot  control  the  muscles  which  fix  the  eyes 
together  on  one  object,  so  he  sees  a  separate  image  with 
each  eye.  The  eyeballs  roll,  and  the  images  he  sees  ap- 
pear to  be  unsteady.  A  long -continued  use  of  alcoholic 
liquors  tends  to  permanent  paralysis  or  unsteadiness  of 
the  muscles.  By  impairing  digestion  the  muscles  do  not 
receive  proper  nourishment  and  are  thus  in  time  weak- 
ened. 


BONES    AND    MUSCLES. A    REVIEW.  29 

8.  Tobacco  on  the  Muscles.  —  Those  who  use  tobacco  to 
excess  are  frequently  troubled  with  trembling  or  nervousness, 
caused  ~by  the  effect  of  the  tobacco  on  the  muscles  through 
the  nervous  system.  Young  persons  are  more  apt  to  be 
injured  than  those  in  middle  or  old  age. 


LESSON  10. 
Bones  and.  Muscles.  —  A  Review. 

[To  TEACHER  AND  PUPIL.  —  Frequent  reviews  are  important.  If  the 
pupil  can  answer  in  an  intelligent  manner  the  majority  of  the  following 
questions,  he  certainly  knows  a  good  deal  about  bones  and  muscles.  This 
lesson  may  be  divided  into  two  or  three  lessons  if  the  teacher  think  proper.] 

1.  How  does  a  bone  differ  from  a  piece  of  wood  ?    From 
a  stone  ? 

2.  What  does  a  hot  fire  remove  from  a  bone?     How 
does  a  burned  bone  differ  from  one  that  is  not  burned  ? 
What  does  an  acid  remove  from  a  bone  ?     How  does  a 
bone  which  has  been  soaked  in  acid  differ  from  one  that 
has  not  ? 

3.  What  proportion  of  a  bone  is  gelatine  ?     What  pro- 
portion is  earthy  matter  ?     What  qualities  does  the  gela- 
tine give  to  bone  ?     What  does  the  earthy  matter  give  ? 

4.  State  the  differences  between  young  and  old  bones. 
Suppose  the  bones  of  a  grown  man  were  exactly  like  those 
of  a  child,  what  would  be  the  result  ?     Suppose  the  bones 
of  a  child  were  exactly  like  those  of  an  old  man,  what 
would  very  likely  happen  ? 

5.  Can  you  describe  the  appearance  of  a  slice  of  bone 
under   the   microscope  ?     What    are    Haversian   canals  ? 
What  are  canaliculi  ?     What  are  lacunae  ? 


30  PHYSIOLOGY    FOR    BEGINNERS. 

6.  What  are  bones  in  an  early  stage  of  their  growth  ? 
The  process  of  changing  from  their  first  condition  to  true 
bone  is  called  ossification.     When  does  ossification  take 
place  ? 

7.  What  covers  bones  ?     From  what  do  they  get  their 
nourishment  ? 

8.  What  is  the  skeleton  ?     Why  does  a  human  body 
need  a  skeleton  ?     What  protects  the  delicate  and  soft 
parts  of  the  body  from  injury  ? 

9.  How  do  bones  aid  in  the  movements  of  the  body? 
Would  muscles  be  of  any  use  without  bones  ? 

10.  Name  some  of  the  uses  to  which  animal  bones  may 
be  put.     What  is  shoe-blacking  made  from  ? 

11.  How  many  bones  in  the  body  ?     How  many  are 
single  ?     How  many  in   the    central  line  of  the  body  ? 
How  many  pairs  of  bones  are  there  ? 

12.  Write  the  names  of  as  many  bones  of  the  head  as 
you  can  call  to  mind.     What  bone  forms  the  forehead  ? 
What  ones  are  used  in  chewing  the  food  ?     Where  is  the 
vomer?     The  ethmoid?     The  temporal? 

13.  How  many  bones  in  the  head  ?     In  the  face  ?     In 
the  trunk  ?     In  the  upper  limb  ?     In  the  lower  limb  ? 
In   the   arm  ?     In   the   hand  ?     In   the  wrist  ?     In  the 
ankle?     In  the  foot? 

14.  What  is  a  vertebra  ?    What  bones  make  the  thorax  ? 
What  the  pelvis  ?     Where  is  the  sacrum  ? 

15.  What  bone  in  the  leg  corresponds  to  the  humerus 
of  the  arm  ? 

16.  How  does  alcohol  affect  the  bones  ?     Tight  cloth- 
ing ?     Why  should  you  sit  and  stand  erect  ? 

17.  What  is  the  advantage  of  so  many  bones  ? 

18.  Describe  ligaments.     In    a   sprained   ankle  what 
part  is  injured  ? 


THE    MOUTH    AND    THE    TEETH.  31 

19.  What  is  the  use  of   ligaments?     Of  cartilage  in 
joints  ? 

20.  What  is  synovia  ?     What  is  its  use  ?     Describe  a 
ball-and-socket  joint  and  give  an  example. 

21.  What  are  muscles  ?     How  many  are  there  ?    What 
are  tendons  ?     What  are  they  for  ?     Why  are  they  some- 
times longer  than  the  muscles  ? 

22.  How  does  a  muscle  fiber  look  under  the  micro- 
scope ? 

23.  How  do  muscles  act  ?     What  relation  do  muscles 
have  to  bones  ?     Name  some  of  the  uses  of  muscles. 

24.  Why  should  we  exercise  ?     Why  should  we  rest  ? 
Why  is  violent  exercise  unadvisable  ? 

25.  Why  does  the  drunken  man  stagger  ?     Why  does 
he  imagine  others  drunk  ?     Why  does  he  sometimes  see 
double  ? 


LESSON  11. 
The  Mouth  and  the  Teeth. 

i.  The  Mouth.  —  The  mouth  is  for  the  reception  of 
food,  although  in  man  it  answers  other  purposes  as  well. 
It  is  the  place  where  articulate  sounds  are  made  principally, 
by  the  help  of  the  tongue,  teeth,  and  lips.  The  tongue, 
when  at  rest,  forms  the  principal  part  of  the  floor  of 
the  mouth.  The  roof  of  the  mouth  is  formed  by  a  part  of 
the  superior  maxillary  bone  and  part  of  the  palate  bone. 

The  back  part  of  the  mouth  is  called  thefau-ces.  It  has 
an  opening  into  a  cavity  called  the  pliar-ynx.  From  the  top 
of  this  opening  hangs,  like  a  little  curtain",  the  u-vu-la,  or 
hanging  palate,  and  on  either  side  are  the  ton-sils,  two 
peculiar  glands  the  uses  of  which  are  not  known.  They 


32 


PHYSIOLOGY    FOR   BEGINNERS. 


sometimes  become  inflamed,  producing  the  disease  known 
as  quinsy  or  ton-sil-i-tis.  The  lips  form  the  front  of  the 
mouth  and  the  cheeks  the  sides.  Each  cheek  is  mainly 
made  up  of  a  muscle,  which,  when  it  contracts,  keeps  the 
food  between  the  teeth.  It  is  brought  into  use  in  blowing 


FIG.  7. 


a  trumpet,  hence  it  is  called  the  buo-cin-a-tor,  or  trumpeter. 
The  entire  inside  of  the  mouth  is  lined  with  mucous 
membrane,  which  will  be  explained  in  another  place,  as  it 
is  only  a  part  of  the  membrane  that  lines  the  whole  of 
the  digestive  tube,  or  canal 


THE  MOUTH  AND  THE  TEETH.  33 

2.  The  Temporary  Teeth. — Usually,  when  a  child   is 
about  seven  months  old,  two  teeth  appear  in  the  front  part 
of  the  lower  jaw,  and  shortly  after  two  above  them  in  the 
upper  jaw.     A  few  months  later  one  appears  on  each  side 
of  the  two  central  ones,  above  and  below,  making  four 
more.     At  the  end  of  the  second  or  third  year,  sometimes 
later,  there  will  be  twenty  teeth,  ten  in  each  jaw.     At  the 
age  of  six  years,  or  later,  these  teeth  begin  to  come  out, 
and  others  grow  up  to  take  their  places.     These  first  teeth 
are  called   temporary,  or  milk  teeth.     The  roots  of   the 
temporary  teeth  are  absorbed ;  that  is,  the  material  which 
composes  them  is  torn  down  gradually  and  carried  away 
in  the  blood.     This  absorption  is  caused  by  the  new  teeth 
pressing  against  them  from  below.     When  the  root  is 
nearly  all  absorbed,  the  tooth  becomes  loose  and  falls  out 
or  is  removed.     It  sometimes  happens  that  the  new  teeth 
begin  to  grow  out  at  the  side  of  the  old  ones,  and  if  the 
old  ones  are  not  pulled  out  crooked  teeth  will  be  the  result. 

3.  The  Permanent  Teeth. — There  are  thirty-two  of  the 
second,  or  permanent,  set  of  teeth,  sixteen  in  each  jaw. 
There  are  four  kinds  of  teeth,  each  kind  differing  in  shape 
and  position  and  used  for  different  purposes.     The  four 
front  teeth  in  each  jaw  are  called    in-ci-sors    (cutters). 
They  are  thin,  broad,  and  sharp,  somewhat  like  a  chisel. 
They  are  for  the  purpose  of  cutting  the  food.     On  each 
side  of  each  set  of  incisors  is  one   ca-nine  (dog)  tooth, 
making  four  in  all.     They  are  pointed  and  a  little  longer 
than  the  other  teeth.     They  help  to  seize  and  tear  the 
food.     In  the  dog  and  cat  they  are  very  long  and  sharp 
and  are  called  "  tushes."     Behind  each  canine  tooth  are 
two  bi-cus-pids  (two-pointed),  making  eight  in  all.     They 
have  each  two  points  and  are   partly  for  tearing    and 


34  PHYSIOLOGY  FOR  BEGINNERS. 

partly  for  grinding  and  crushing  the  food.  Back  of  the 
bicuspids  are  the  mo-lars  (grinders),  six  in  each  jaw. 
Those  in  the  upper  jaw  have  five  points,  and  those  in  the 
lower  jaw  four.  They  are  larger  and  stronger  than  the 
other  teeth  and  are  for  the  purpose  of  crushing  and 
grinding  the  food. 

4.  Parts  of  a  Tooth. — Each  tooth  has  a  crown,  or  top 
portion,  a  root,  OY  fang,  which  is  buried  in  the  jaw  bone, 
and  a  neck,  or  slightly  narrowed  portion,  between  crown 
and  root,  covered  by  the  gums.      The  gums  consist  of  a 
fibrous  material  covered  with  mucous  membrane.      The 
incisor,  canine,  and  bicuspid  teeth  have  each  but  one  root. 
The  upper  molars  have  three  roots,  the  lower  two. 

5.  The  Structure  of  a  Tooth.  —  Each  tooth  contains  a 
cavity,  which  during  life  is  filled  with  a  soft  substance 
called  dental  pulp.     This  contains  nerves  and  blood  ves- 
sels, and  from  it  the  tooth  gets  its  nourishment.      The 
body  of  the  tooth  consists  of  white  substance  harder  than 
bone,  called  den-tine.      The  crown  of  the  tooth  is  covered 
with  a  very  hard  substance,  the  en-am-el.      It  is  not  only 
the  hardest  substance  in  the  human  body,  but  the  hardest 
in  the  animal  and  vegetable  kingdoms,  and  one  of  the 
most  durable.      It  is  harder  than  iron  and  most  of  the 
metals.     The  root  of  the  tooth  is  covered  with  a  substance 
called  cement,  which  is  very  similar  to  bone. 

6.  The  Time  and  Order  of  Appearance  of  the  Teeth. — 

The  time  differs  in  different  persons,  but  the  order  is 
always  the  same.  Usually  the  temporary  teeth  appear  as 
follows :  — 

7th  month,  two  middle  incisors. 

9th  month,  two  side  incisors. 


THE    ROAD    TO    THE    STOMACH.  35 

13th  month,  first,  or  front,  molars. 
18th  month,  canines. 

One  and  a  half  to  three  years,  last  molars. 
The  permanent  teeth  appear :  — 
6  i  years,  first  molars. 
7th  year,  two  middle  incisors. 
8th  year,  two  side  incisors. 
9th  year,. first  bicuspid. 
10th  year,  second  bicuspid, 
llth  to  12th  year,  canine. 
12th  to  13th  year,  second  molars. 
17th  to  21st  year,  last  molar. 

The  last  molar  is  called  the  wisdom  tooth.  It  is  usually 
smaller  than  the  other  molars. 

7.  Uses  of  the  Teeth. —  You  know  that  the  teeth  are 
for  the  purpose  of  dividing  the  food  and  preparing  it  for 
swallowing.  In  animals  they  serve  to  secure  their  food 
and  for  defence.  In  man  they  help  to  articulate  sounds. 
Certain  letters  cannot  be  pronounced  without  the  aid  of 
the  teeth.  They  also  add  to  the  beauty  of  the  human 
face. 


LESSON  12. 
The  Road  to  the  Stomach. 

i.  The  Salivary  Glands.  — The  mouth  is  the  beginning 
of  a  tube  which  is  about  thirty  feet  in  length,  called  the 
alimentary  (food)  canal.  Certain  glands  manufacture 
fluids  from  the  blood  and  pour  them  into  this  canal  at 
various  places.  These  fluids  are  the  principal  agents  in 
digesting  the  food.  The  first  fluid  which  is  poured  into 
the  alimentary  canal  is  the  saliva.  This  fluid  is  secreted, 


36  PHYSIOLOGY   FOE   BEGINNERS. 

or  manufactured,  in  certain  glands  called  salivary  glands. 
There  are  three  pairs  of  them.  The  pa-rot-id  is  the  larg- 
est. It  lies  beneath  the  skin  just  in  front  of  the  ear,  and 
pours  its  secretion  into  the  back  part  of  the  mouth  through 
a  tube  called  Stenson's  duct.  The  next  largest  is  the  sub- 
maxillary ,  just  below  the  angle  of  the  lower  jaw.  It  has 
a  duct,  or  outlet,  also.  The  sublingual  is  the  other  gland, 
lying  just  beneath  the  tongue.  It  has  a  number  of  small 
ducts.  These  glands  consist  of  many  little  bags  arranged 
something  like  a  bunch  of  grapes ;  each  tiny  bag  has  a 
tube,  which  unites  with  others ;  and  finally  all  empty  into 
the  duct  of  the  gland.  The  saliva  changes  starch  to  sugar. 

2.  The  Pharynx.  — We  have  said  that  in  the  back  part 
of  the  mouth  was  an  opening  into  the  pharynx.     This 
is  a  short,  wide  tube,  composed  of  muscles  and  lined  with 
mucous  membrane.     It  has  seven  openings  :   one  to  the 
mouth  above ;  one  to  the  gullet,  or  e-soph-a-gus,  below ; 
one  to  the  larynx,  or  beginning  of  the  windpipe ;  two  to 
the  cavities  of  the  nose ;  and  two  to  the  Eu-sta-chi-an 
tubes,  which  lead  to  the  middle  ear.      The  pharynx  re- 
ceives the  food  from  the  mouth  and  passes  it  into  the 
esophagus. 

3.  The  Esophagus. —  This  is  the  tube  through  which 
the  food  passes  into  the  stomach.     It  is  about  nine  inches 
long  and  lies  behind  the  windpipe,  the  heart,  and  the 
lungs.     It   is    composed    of    muscular    fibers    lined   with 
mucous   membrane.     The   muscular   fibers  of   the  outer 
layer  run  lengthwise,  and  those  of  the  inner  layer  run 
circularly.      The  walls  are  soft  and  elastic  and  lie  close 
together  except  when  food  is  passing.      When  a  portion 
of  food  enters  the  esophagus,  a  ring  of  muscular  fibers  con- 
tracts behind  it,  pushing  it  along  a  little  way ;  and  this  is 


THE    STOMACH.  37 

followed  by  the  contraction  of  another  ring,  and  so  on, 
until  the  food  is  forced  into  the  stomach.  A  person  can 
swallow  when  standing  on  his  head  just  as  well  as  in  the 
natural  upright  position,  as  the  muscles  will  force  the 
food  along.  Children  sometimes  get  hold  of  acids  or 
alkalies,  or  other  strong  and  poisonous  substances,  and 
drink  them.  If  the  result  is  not  death,  it  may  be  a 
destruction  of  part  of  the  mucous  membrane  of  the  mouth, 
pharynx,  and  esophagus ;  and  when  healing  takes  place,  the 
esophagus  (because  its  walls  lie  in  contact  with  each  other) 
grows  partly  or  completely  shut,  so  that  little  or  no  food 
can  be  swallowed.  Turn  to  the  lesson  on  Digestion,  and 
see  what  is  there  said  about  the  nourishing  of  the  person 
in  such  a  case. 

4.  Remember  that  the  food  is  taken  into  the  mouth, 
chewed,  or  masticated,  by  the  teeth,  aided  by  the  tongue 
and  cheeks,  which  help  to  keep  it  between  the  teeth,  and 
by  the  saliva,  which  moistens  it ;  then  it  passes  into  the 
pharynx,  and  we  have  no  longer  control  of  it,  and  from 
there  to  the  esophagus,  which  carries  it  into  the  stomach, 
where  it  falls  in  little  rounded  masses  called  boluses. 
Here  it  undergoes  further  preparation. 


LESSON  13. 
Trie  Stomach. 

i.  Location. —  This  important  organ  of  digestion  lies 
in  the  upper  and  mainly  in  the  left  part  of  the  cavity  of 
the  abdomen.  It  must  be  remembered  that  the  space 
between  the  neck  and  the  hips  is  divided  into  two  large 
cavities  by  a  muscular  partition  called  the  diaphragm. 


38  PHYSIOLOGY    FOR    BEGINNERS. 

The  cavity  above  the  diaphragm  is  called  the  thoracic 
cavity  and  contains  the  heart  and  lungs ;  and  the  space 
below  is  called  the  abdomen,  or  abdominal  cavity,  and 
contains  the  stomach,  intestines,  liver,  spleen,  and  kid- 
neys. The  stomach  is  an  enlargement  of  the  alimentary 
canal  and  a  continuation  of  the  esophagus. 

2.  Size   and   Shape. — The    stomach   is   about   twelve 
inches  long,  four  inches  broad,  and  two  inches  thick,  and 
holds  about   three   pints  when   moderately  full.      It   is 
somewhat  in  the  shape  of  a  pear,  larger  at  the  upper,  or 
left,  end.     The  place  where  the  esophagus  ends  and  the 
stomach  begins  is  called  the  car-di-ac  orifice ;  and  at  the 
opposite  end,  where  the  intestine  begins,  is  the  py-lo-ric 
orifice.     A  fold  of  the  mucous  lining  of  the  stomach  forms 
a  kind  of  valve  or  door.      This  is  called  the  py-lo-rus 
(gate-keeper) . 

3.  Structure.  —  The  walls  of  the  stomach  are  made  up 
of  four  layers  or  coats.     The  inner  is  a  mucous  membrane, 
continuous  with  the  lining  of  the  esophagus  and  intestines. 
Next  to  this  is  a  layer  of  loose  tissue  called  the  cellular 
coat,  and  next  to  this  is  the  muscular  coat.     This  consists 
of  fibers,  some  of  which  run  lengthwise,  some  circularly, 
and  some  diagonally.     The  outer  coat  is  called  a  serous 
membrane,  being  a  part  of  the  membrane  which  lines  the 
abdominal  cavity  and  covers  all  organs  within  it.     The 
mucous  membrane  contains  many  folds,  or  wrinkles,  and 
cavities,  which   greatly  increases   the    surface.      Amidst 
these  folds  are  numerous  little  glands  which  secrete  the 
gastric  juice. 

4.  Gastric  Juice.  —  The  gastric  (stomach)  juice   is   a 
clear,  watery  liquid,  one  of  the  principal  agents  in  dig 


THE    INTESTINES.  39 

solving  and  preparing  the  food.  It  contains  a  peculiar 
substance  called  pep-sin,  which  has  the  power  of  changing 
albuminous  substances  (that  is,  substances  resembling  the 
white  of  an  egg  in  chemical  nature)  into  albuminose,  in 
which  condition  they  are  fit  to  be  absorbed  and  become  a 
part  of  the  blood.  Gastric  juice  has  no  effect  on  starch  and 
sugar,  nor  on  fats  and  oils.  These  are  changed  by  other 
fluids  of  digestion. 


LESSON   14. 
The  Intestines. 

1.  The  Small  Intestine. — We  have  seen  that  the  ali- 
mentary canal  is  first  a  cavity,  the  mouth;  then  a  short, 
wide  tube,  the  pharynx;   then  a  long,  narrow,  straight 
tube,    the    esophagus;    then   a   large   bag,   the   stomach. 
Now  it  narrows  down  again  to  a  tube  about  twenty  feet 
long,  coiled  up  in  a  mass  in  the  center  of  the  abdomen. 
This  is  divided,  for  convenience  of  study,  into  three  parts, 
the  du-o-de-num,  the  je-ju-num,  and  the  il-e-um. 

2.  The  Duodenum.  —  This  is  the  part  of  the  small  intes- 
tine next  to  the  stomach  and  is  so  called  from  the  Latin 
word  for  twelve,  as  it  is  about  as  long  as  the  width 
of  twelve  fingers,  or  about  ten  inches.    It  is  very  crooked, 
extending    first   upward   from   its   connection   with    the 
stomach,  then  backward  and  to  the  right,  then  to  the  left, 
where  it  takes  the  name  of  jejunum. 

3.  The  Jejunum.  — This  part  of  the  small  intestine  was 
so  named  from  the  fact  that  it  is  always  found  empty 
after  death,  from  a  Latin  word  meaning  "  empty."     It  is 


40 


PHYSIOLOGY    FOR   BEGINNERS. 


about  seven  feet  in  length  and  is  a  little  narrower  than 

the  duodenum. 

t  4.    The  Ileum.  — The 

remaining  part  of  the 
small  intestine  is  called 
the  ileum,  from  a  word 
meaning  "  to  twist/'  be- 
cause it  lies  in  many 
folds  and  coils. 

5.  Structure  of  the 
Small  Intestine.  —  The 
walls  of  the  small  in- 
testine are  similar  to 
that  of  the  stomach, 
there  being  four  coats : 
the  inner,  mucous  ;  next, 
muscular  ;  next,  cellular; 
and  outer,  serous.  The 
mucous  and  cellular 
coats  are  wrinkled  by 
numerous  folds,  and 
these  folds  are  covered 
with  very  tiny  little  pro- 
jections as  thick  as  the 
fibers  of  a  piece  of  vel- 
vet. These  little  projec- 
tions are  called  vil-li 
(singular,  villus,  mean- 
ing a  tuft  of  hair).  By  this  arrangement  of  folds  and 
villi  an  enormous  amount  of  surface  is  gained,  a  point  of 
great  importance  in  absorption,  which  will  be  explained 
in  another  lesson.  Small  glands  are  in  the  mucous  coat. 
They  secrete  the  intestinal  juice. 


THE    ALIMENTARY    CANAL. A    REVIEW.  41 

6.  The  Large  Intestine.  —  This  portion  of  the  aliment- 
ary canal   does  not  appear   like   a    simple   enlargement 
of  a  tube,  but  like  a  wide  tube  closed  at  one  end;  and 
the  small  intestine,  like  a  smaller  tube,  entering  it  at  a 
point  a  little  way  from  the  closed  end.     The  parts  of  the 
large  intestine  are  the  coe-cum,  the  co-Ion,  and  the  rec-tum. 

7.  The  Coecum.  —  This  is  the  closed  end  of  the  large 
intestine,  or  that  part  which  projects  beyond  the  placo 
where  the  small  intestine  enters.     It  is  so  called  because 
closed  at  one  end,  the  word  coecum  meaning  "  blind."     At 
its  closed  end  is  a  small  tube  about  as  thick  as  a  goose 
quill,  called  the  ver-mi-form  (worm-like)  appendix.     One 
should  never  swallow  cherry  stones  and  other  hard  seeds 
of  fruits,  as  they  have  been  known  to  lodge  in  this  little 
tube  and  cause  serious  disease  and  even  death. 

8.  The  Colon  and  Rectum.  —  As  you  see  in  the  picture, 
the   colon   lies   around   the    small   intestine,   having    an 
ascending,  a  transverse,  and  a  descending  portion,  and  end- 
ing, by  a  peculiar  crook,  in  a  straight  tube,  the  rectum. 

9.  Structure  of  Large  Intestine.  —  There  is  very  little 
difference  in  the  walls  of  the  large  and  those  of  the  small 
intestines.     The  large  intestine  has  many  folds,  but  no 
villi. 

LESSON   15. 
The  Alimentary  Canal. — A  Review. 

1.  What  is  the  use  of  the  mouth  ?  What  forms  the 
floor  of  the  mouth?  The  roof?  The  sides?  What  is 
the  back  part  of  the  mouth  called  ?  What  is  the  uvula  ? 
What  are  the  tonsils  ? 


42  PHYSIOLOGY    FOR    BEGINNERS. 

2.  How  many  temporary  teeth  are  there  ?     Where  do 
they  first  appear  ?     What  makes  them  come  out  ? 

3.  How  many  permanent  teeth  ?     Describe  the  inci- 
sors ;   the  canine  teeth.      What  teeth  stand  behind  the 
canines  ?     Describe  the  molars.     Name  the  uses  of  each 
of  the  kinds  of  teeth. 

4.  What  are  the  parts  of  a  tooth?      What   are  the 
gums  ?     What  is  found  in  the  cavity  of  a  living  tooth  ? 

5.  What  is  enamel  ?    Dentine  ?     What  is  the  hardest 
substance  in  the  organic  world  ?     Can  you  cut  the  enamel 
of  your  teeth  with  a  knife  ?     No ;  but  you  may  break  a 
piece  of  it  off  by  striking  it  with  a  piece  of  metal.     Do 
not  use  a  metal  toothpick,  or  crack  nuts  with  your  teeth. 

6.  State  the  order  in  which  the  different  kinds  of  tem- 
porary teeth  appear.     When  do  they  begin  to  appear? 
When  has  a  child  a  full  set  ol  temporary  teeth  ? 

7.  When    does    the    first    permanent    tooth    appear? 
What  happens  to  the  temporary  tooth  that  is  in  its  way  ? 
What  is  the  wisdom  tooth  ? 

8.  State  three  uses  of  teeth.     What  is  the  alimentary 
canal  ?     Its  length  ?     Name  and  locate  the  three  pairs  of 
salivary  glands. 

9.  What  is  the  use  of  the  salivary  glands  ?     You  will 
learn  more  about  saliva  in  the  lesson  on  Digestion. 

10.  Describe  the  pharynx.     Name  its  openings.    What 
is  the  use  of  the  esophagus?     How  is  the  food  carried 
into  the  stomach  ?     A  stone,  if  unsupported,  falls  toward 
the  earth,  we  say,  by  the  force  of  gravity.    Does  the  force 
of  gravity  have  anything  to  do  with  swallowing  ? 

11.  What  part  of  the  preparation  of  the  food  takes 
place   in   the    mouth  ?     What   then   receives   the   food  ? 
What  next  ?     What  next  ? 

12.  Locate  the  stomach.     What  relation  has  it  in  loca- 


THE    LIVER,    PANCREAS,    AND    SPLEEN.  43 

tion  to  the  heart  and  lungs  ?     What  organs  lie  below  the 
diaphragm  ?     What  above  ? 

13.  State  the  size  and  shape  and  name  the  orifices  of 
the  stomach.     What  is  the  pylorus  ? 

14.  Name  the  coats  of  the  stomach  in  proper  order. 
How  is  the  surface  of  the  interior  of  the  stomach  in- 
creased ? 

15.  What  does   the    stomach  secrete  ?     What   is   the 
name  of  the  peculiar  fluid  which  helps  digest  (prepare) 
the  food  in  the  stomach  ?     Does  it  affect  starch  ?     What 
fluid  does  act  on  starch  ? 

16.  What  is  the  widest  portion  of  the  tube  called  the 
alimentary  canal  ?  What  is  the  duodenum  ?  The  jejunum  ? 
The  ileum  ?     What  is  the  length  of  the  small  intestine  ? 
Of  the  large  intestine  ? 

17.  State  the  resemblances  and  differences  between  the 
large  and  small  intestines,  —  in  length,  in  thickness,  and 
in  structure.     Name  the  parts  of  the  large  intestine. 

18.  What  are  villi  ?     What  is  a  villus  ?     What  is  the 
vermiform  appendix  ? 


LESSON  16. 
The  Liver,  Pancreas,  and  Spleen. 

i.  What  are  Glands  ?  —  Glands  are  organs  which  either 
separate  materials  from  the  blood  or  actually  manufacture 
certain  fluids  by  combining  certain  elements  existing  in 
the  blood.  These  fluids  usually  serve  important  purposes 
in  the  body.  Some  glands  are  mere  depressions  in  the 
mucous  membrane,  as  the  glands  which  secrete  the  mucus ; 
others  are  complicated  arrangements  of  cells  and  tubes, 
as  the  liver. 


44  PHYSIOLOGY    FOR   BEGINNERS. 

2.  The  Location,  Size,  etc.,  of  the  Liver.  —  You  have  all 
seen  the  liver,  or  a  part  of  the  liver,  of  an  ox  or  pig. 
The  human  liver  resembles  the  liver  of  these  animals  in 
general  appearance.     It  is  located  in  the  right  and  upper 
portion  of  the  abdominal  cavity,  just  beneath  the  dia- 
phragm.    Its  length  from  side  to  side  is  ten  or  twelve 
inches,  its  breadth  from  before  backward  is  six  or  seven 
inches,  and  its  thickness  from  above  downward  is  about 
three  inches.     In  a  grown  person  it  weighs  three  or  four 
pounds. 

3.  Structure  of  the  Liver. — To  the  naked  eye  the  liver 
appears,  when  cut  through,  as  a  reddish  brown  mass,  with 
tubes  scattered  here  and  there  through  it.     Careful  ex- 
amination by  the  aid  of  the  microscope  shows  that  the 
liver  is  made  up  of  minute  rounded  cells,  held  together 
by  fibrous  tissue,  and  intermingled  with  a  dense  network 
of  tubes.     These  tubes  are  the  branches  of  the  various 
vessels  of  the  liver,  which  are  as  follows :  (1)  The  por-tal 
vein,  which  is  made  up  of  branches  coming  from  the 
stomach,  intestines,  and  spleen.     It  penetrates  the  liver 
and  divides  again  and  again,  until  it  reaches  by  fine  tubes 
every  part.     (2)  The  he-pat-ic  artery,  which  supplies  the 
liver  with  blood  just  as  every  other  organ  is  supplied. 
(3)  The  hepatic  veins,  of  which  there  are  several,  carry  the 
blood  out  of  the  liver  which  has  been  carried  into  it  by 
the  hepatic  artery  and  portal  vein.    (4)  The  hepatic  duct, 
which  begins  among  the  cells  of  the  liver  as  a  network, 
and  finally  unites  into  one  tube.     This  duct  conveys  the 
bile  which   is    secreted   by   the   liver,   to   the    intestine. 
(5)  The  lymphatics,  which  form  a  part  of  a  system  which 
spreads  through  the  body.     They  will  be  explained  in 
another  lesson. 


THE    LIVER,    PANCREAS,    AND    SPLEEN.  45 

4.  The  Bile.  —  This  is  one  of  the  important  fluids  of 
the  digestive  system.     It  is  a  clear,  yellowish,  or  greenish 
yellow,  watery  fluid.     It  is  manufactured  in  the  cells  of 
the  liver,  passes  into  the  fine  branches  of  the  hepatic  duct 
and  finally  into  the  small  intestine  through  the  common 
bile  duct.     This  duct  is  made  by  the  joining  of  the  hepatic 
duct  and  the  cystic  duct,  which  comes  from  the  bile  cyst, 
or  gall-bladder.     This  is  a  bag  which  lies  on  the  under 
side  of  the  liver,  and  is  for  the  purpose  of  containing  the 
bile  when  digestion  is  not  going  on.     Thus,  while  food  is 
being  digested  in  the  intestine,  the  bile  is  gradually  pass- 
ing down  from  the  liver  into  the   intestine ;   but  when 
there  is  no  food  to  be  digested  in  the  intestine,  the  common 
bile  duct  closes.     But  the  secretion  goes  on  all  the  time 
in  the  liver,  and  there  must  be  some  place  for  the  bile  to 
be  deposited.     This  place  is  the  gall-bladder.     The  bile 
then  backs  up  through  the  cystic  duct  and  fills  the  gall- 
bladder, to  pass  down  again  when  required  in  the  intes- 
tine.    This  arrangement  is  something  like  a  mill-pond, 
which  accumulates  a  supply,  or  u  head,"  of  water  while 
the  mill  is  not  running,  to  be  used  when  the  mill  is 
running. 

5.  The  Uses  of  the  Liver.  — The  liver  secretes,  or  manu- 
factures, bile  ;  but  this  is  but  one  of  its  uses.     It  has  other 
and  more  important  uses.     It  has  the  peculiar  power  of 
storing  up  heat-making  material.     The  heat-making  food 
is  mostly  sugar,  either  taken  as  sugar  itself  or  in  the  form 
of  starch,  which  is  converted  into  sugar  by  the  saliva  and 
pancreatic  fluid.     This  sugar  all  passes  into  the  liver  with 
the  blood  and  is  there  converted  into  an  insoluble  form, 
called  gly-co-gen  (a  word  meaning  "sugar  producer,"  so 
called   because  it  is   readily  converted   back   to   sugar). 


46  PHYSIOLOGY    FOR    BEGINNERS. 

Starch  cannot  be  absorbed  and  taken  into  the  blood.  It 
is,  therefore,  converted  into  sugar  in  the  alimentary  canal 
and  absorbed  into  the  blood.  Sugar  cannot  be  stored  up, 
as  it  dissolves  so  readily.  It  is,  therefore,  converted  into 
glycogen  for  the  purpose  of  storage,  and  this  glycogen  is 
converted  back  to  sugar  as  the  body  demands  it.  If  it 
were  not  for  this  wise  arrangement,  shortly  after  diges- 
tion the  blood  would  have  more  heat-making  material 
than  could  be  used,  and  during  the  period  of  fasting  there 
would  not  be  enough.  The  liver,  then,  acts  as  a  bank, 
receiving  deposits  in  large  sums  and  paying  them  out  in 
small  sums,  as  demanded. 

6.  The  Pancreas.  —  This  gland  is  called  the  "  sweet- 
bread" in  animals.    The  word  pancreas  means  "all  flesh," 
so  named  from  its  appearance.    It  lies  behind  the  stomach, 
and  is  somewhat  like  a  dog's  tongue  in  shape.     It  is  six 
or  eight  inches  long,  one  and  a  half  inches  broad,  and 
from  one-half  to  an  inch  thick,  and  weighs  about  three 
ounces.     In  structure  it  is  very  similar  to   the  salivary 
glands.     It  secretes  a  fluid,  which,  like  the  saliva,  con- 
verts starch  into  sugar  and,  like  the  gastric  juice,  converts 
albuminous  foods  into  allwminose,  and  also  acts  upon  the 
fats,  changing  them  into  a  form  capable  of  being  absorbed. 
The  fluid  passes  out  by  a  duct  into  the  duodenum. 

7.  The  Spleen.  —  As  very  little  is  known  of  the  use  of 
this  organ,   we  need  say  but  little   about   it.      It  is  an 
oblong,  dark-colored  body,  somewhat  in  appearance  like 
the  liver,  and  weighs  usually  about  seven  ounces ;  but  in 
certain  diseases  it  has  been  known  to  increase  to  twenty 
pounds  in  weight.      It  secretes  no  fluid,  but  numerous 
blood  vessels  pass  into  it  and  through  it  and  out  again. 
It  is  supposed  to  effect  some  changes  in  the  blood  and  to 


DIGESTION.  47 

act  as  a  reservoir  for  the  increased  amount  of  blood  pro- 
duced during  digestion. 


LESSON  17. 
Digestion. 

1.  What  is  Digestion?  — We  have  used  this  word  sev- 
eral times  already  in  this  book,  and  you,  perhaps,  have 
some  idea  of  its  meaning.     You  will  say  that  it  is  the 
process  of  preparing  the  food  to  be  used  by  the  body. 
The  word  digest  means  literally  "  to  cook,"  but  digestion 
is  a  different  kind  of  preparation.     The  preparation  is 
such  a  change  on  the  food  as  will  render  it  capable  of 
being  absorbed ;  that  is,  taken  into  the  blood  vessels  which 
circulate  it  through  the  body.      Some  portions  of  some 
kinds  of  food  are  not  digested  at  all.     The  grape  sugar 
which  is  found  in  fruits  is  simply  absorbed,  also  the  water, 
which  may  be  considered  a  part  of  the  food.     Other  sub- 
stances, however,  could  not  pass  into  the  blood  vessels 
and  must  undergo  a  chemical  change.      Digestion  also 
includes  the  mechanical  division  of  the  food;  that  is,  the 
crushing,  grinding,  breaking,  or  dissolving  action  necessary 
to  reduce  it  to  a  fine  state,  so  that  the  fluids  of  digestion 
may  act  upon  it. 

2.  Steps   in   the  Process  of   Digestion. — The  food  is 
first  taken  into  the  mouth  and  there  chewed,  or  masticated, 
and  at  the  same  time  thoroughly  mixed  with  the  saliva. 
The  next  step  is  swallowing,  which  is  simply  the  process 
of  passing  from  the  mouth  to  the  pharynx  and  through 
the  esophagus  to  the  stomach. 


48  PHYSIOLOGY    FOR    BEGINNERS. 

In  the  stomach  the  food  is  thoroughly  mixed  with  the 
gastric  juice  and  is  reduced  to  a  half-fluid  state  called 
chyme.  This  mixing  and  dissolving  action  is  aided  by  a 
peculiar  churning  motion  of  the  stomach,  caused  by  con- 
tractions of  the  muscular  fibers  in  its  walls.  By  this 
action  the  food  is  made  to  pass  round  and  round  in  the 
stomach  from  one  end  to  the  other  and  back  again,  the 
pylorus,  or  valve  at  the  lower  end,  preventing  the  contents 
from  escaping  into  the  duodenum  until  it  is  thoroughly 
dissolved.  If  there  is  any  solid  substance  which  cannot 
be  dissolved  by  the  stomach,  it  is  apt  to  work  its  way 
through  the  pyloric  valve  and  escape  into  the  duodenum 
before  digestion  is  completed.  The  saliva  does  not  act  in 
the  stomach,  because  it  is  chemically  of  an  opposite  nature 
to  the  gastric  juice  and  cannot  act  in  its  presence.  But 
its  action  is  resumed  in  the  intestine,  where  the  gastric 
juice  is  neutralized  by  the  fluids  found  there. 

The  chyme  passes  into  the  small  intestine  and  is  acted 
upon  by  the  bile,  the  pancreatic  juice,  and  the  intestinal 
juice.  These  fluids  complete  the  process  of  digestion. 
The  part  of  the  chyme  which  can  be  absorbed  and  used  as 
nourishment  is,  after  it  has  been  acted  upon  by  the  intes- 
tinal fluids,  called  chyle.  The  portions  which  are  indi- 
gestible pass  on  in  the  intestine  as  waste  material. 

To  sum  up,  then,  the  steps  in  the  process  of  digestion 
proper  are :  (1)  chewing,  (2)  swallowing,  (3)  stomach 
preparation,  or  chymification,  (4)  intestinal  preparation, 
or  chylification. 

3.  What  is  Chyle  ? —  It  is  a  milky,  white  fluid  contain- 
ing all  the  nourishing  part  of  the  food  except  a  part  of 
certain  portions,  mostly  sugar,  which  has  been  absorbed 
by  the  veins  of  the  stomach.  Its  white  appearance  is 


DIGESTION.  49 

caused  by  the  fat  of  the  food,  which  is  broken  up  into  very 
minute  globules. 

4.  What  is  Absorption  ? —  Though  not  a  part  of  the  proc- 
ess of  digestion  proper,  it  is  intimately  connected  with  it  and 
should  be  thoroughly  understood  before  proceeding  further. 
It  is  the  process  of  sucking  in,  or  taking  up  of,  the  nourish- 
ing part  of  the  food  from  the  alimentary  canal,  by  the 
blood  vessels.  Absorption  is  accomplished  in  two  ways, 
by  the  veins  of  the  mucous  membrane  of  the  alimentary 
canal  and  by  certain  organs  called  lac-te-als.  These  are 
fine  thread-like  tubes,  which  begin  in  the  villi  of  the  small 
intestine  and  unite  with  larger  and  larger  ones  until  they 
finally  empty  into  a  large  tube  called  the  thoracic  duct. 
This  lies  along  the  spinal  column,  back  of  the  stomach 
and  intestines,  and  is  connected  with  one  of  the  large 
veins  of  the  body,  into  which  its  contents  empty.  The 
lacteals  are  for  the  special  purpose  of  absorbing  fats,  which 
cannot  be  absorbed  directly  by  the  blood  vessels.  They 
absorb  other  substances  also.  The  nourishing  parts  of 
the  food,  or,  xin  other  words,  the  digested  food,  then, 
gets  into  the  blood  either  directly  by  absorption  through 
the  veins,  or  indirectly  by  first  passing  through  the  lac- 
teals  and  thoracic  duct  and  then  into  the  veins. 

During  the  short  time  the  food  is  in  the  mouth, 
pharynx,  and  esophagus  there  can  be  but  little  chemical 
change  and  but  little  absorption,  yet  there  is  some  of  both. 
If  certain  poisons  be  taken  in  the  mouth,  they  may  be 
immediately  absorbed  and  produce  death  without  a  par- 
ticle even  reaching  the  stomach.  Thirst  may  be  quenched 
by  merely  holding  water  hi  the  mouth,  and  the  effect  of 
medicine  may  be  obtained  in  a  similar  manner. 

Plants  and  some  of  the  lowest  forms  of  animal  life  do 


50  PHYSIOLOGY    FOR   BEGINNERS. 

not  digest  food,  but  simply  absorb  the  material  which  sur- 
rounds them,  selecting  that  which  is  adapted  to  their  nour- 
ishment. 


LESSON  18. 
Food  and  Drink. 

1 .  What  is  Food  ?  —  This  looks  like  a  very  easy  ques- 
tion to  answer,  yet   it  is  not  so  easy  to  give  a  correct 
answer.     Food  is  whatever  can  be  used  in  building  up  the 
tissues  of  the  body  or  in  furnishing  by  its  combustion  a 
supply  of  animal  heat.     This  gives  rise  to  another  ques- 
tion.    What  is  animal  heat  ? 

2.  Animal  Heat.  — It  is  a  peculiar  fact  that,  no  matter 
how  cold  or  hot  the  temperature  of  the  atmosphere  sur- 
rounding us  may  be  so  long  as  life  lasts  (except  in  some 
cases  of  disease),  the  temperature  of  the  blood  remains 
very  nearly  the  same,  that  is,  about  ninety-eight  degrees 
Fahrenheit.     A  man  may  go  into  an  oven  heated  to  three 
hundred  and  fifty  degrees,  and  again  endure  for  a  time  a 
temperature  of  forty  degrees  below  zero,  and  yet  the  tem- 
perature of  his  blood  will  be  but  slightly  changed.     The 
reason  of  this  is  that  in  the  second  case  more  heat  is  pro- 
duced by  the  combustion  of  material  in  the  body  as  fast 
.as  it  is  conducted   away  by  the  atmosphere,  and  in  the 
ifirst  case  the  perspiration  by  its  rapid  evaporation  cools 
the  body.     Animal  heat  is  heat  produced  by  the  combus- 
tion of  fuel  in  the  body,  the  fuel  being  partly  the  food 
and  partly  the  tissues  of  the  body,  which  are  consumed  to 
make  room  for  new  tissues,  that  are  constantly  being  pro- 
duced. 


FOOD   AND   DRINK.  51 

3.  Assimilation. — This  word  means  "  making  like  or 
similar  to."    It  is  applied  to  the  process  of  building  up  the 
tissues  from  the  material  furnished  by  the  blood.     The 
blood  gets  its  new  material  from  the  food.     The  cells  of 
the  body  are  constantly  changing.     Old  ones  disappear, 
and  the  material  of  which  they  are  composed  passes  out 
of  the  body  and  is  called  waste  material.     The  new  cells 
which  take  their  place  are  made  from  the  new  material 
in  the  blood.     New  material  (food)  is  also  needed  for  the 
increase  in  size  of   the   body.     It  is  said  that  in  seven 
years  all  the  substance  of  the  body  has  been  removed  and 
new  material  taken  its  place.     This  is  a  mere  guess,  as  we 
do  not  know  how  long  it  takes ;  but  we  do  know  that  old 
cells  are  removed  and  new  cells  take  their  places.     The 
rate  at  which  this  change  goes  on  varies  in  different  tis- 
sues.    The  cells  of  the  mucous  membrane  of  the  stomach 
are  said  to  be  renewed  several  times  during  the  act  of 
digestion.     The  bones  and  other  hard  tissues  are  renewed 
more  slowly,  the  enamel  of  the  teeth,  perhaps,  not  more 
than  once  or  twice  in  a  lifetime. 

4.  Food  Classified.  —  All   those  foods   which   tend   to 
produce  heat  in  the  body  we  shall  call  heat-making  foods, 
and  those  which  supply  the  waste  and  build  up  the  tissues 
we   shall   call   tissue-making   foods.      The    heat-making 
foods  are  mainly  those  which  contain  carbon.     They  are 
sugar,  starch,  and  fats.     Oil  is  only  a  fat  which  remains 
liquid  at  ordinary  temperature.     The  tissue-making  foods 
are  mainly  those  that  contain  nitrogen  as  well  as  carbon. 
They  are  often  called  for  this  reason  nitrogenous  foods; 
and,  as  they  resemble  albumen  (a  substance  nearly  pure 
in  the  white  of  an  egg),  they  are  sometimes  called  albu- 
minous foods.     Sugar,  starch,  and  fat  are  also  frequently 


52  PHYSIOLOGY    FOR    BEGINNERS. 

spoken  of  as  carbonaceous  foods.  Sugar  is  found  in  most 
fruits,  a  small  amount  in  grains  and  in  garden  vegetables ; 
but  the  principal  supply  is  from  the  juice  of  the  sugar 
cane  and  from  the  beet  root.  Starch  is  abundant  in  pota- 
toes and  all  grains.  Our  supply  of  fats  comes  from  the 
flesh  of  animals,  from  butter,  and  a  small  amount  from 
grains  and  nuts.  Albuminous  foods  exist  in  the  form  of 
albumen  proper  in  eggs,  fibrin  in  lean  meat,  gelatine  in 
bones  and  fibrous  tissue,  gluten  in  wheat,  legumin  in  peas 
and  beans,  and  casein  in  milk.  Eggs  and  milk  are  perfect 
foods,  as  they  contain  a  proper  proportion  of  heat-making 
and  tissue-making  elements. 

5.  Proper  Selection  of  Food.  —  In  winter  and  in  cold 
countries  our  bodies  lose  heat  rapidly  and  we  need  to  eat 
more  of   the  heat-making  food,  that  is,  substances  con- 
taining sugar,  starch,  and  fat ;  in  summer  and  in  warm 
countries,    a   greater   proportion   of    tissue-making   food. 
The  temperature  of  the  body  is  nearly  always  a  little 
higher  than  the  atmosphere,  even  in  the  warmest  coun- 
tries ;  therefore  the  supply  of  heat-making  food  should  at 
all  times  be  greater. 

6.  Water.  —  All  drinks  that  can  be  taken  in  any  ex- 
cept  very   small   quantities   must    be    composed   in   the 
greater  part  of  water.     Tea,   coffee,  and  chocolate,  the 
common  table  drinks,  are  almost  entirely  water.     Water 
is  necessary :  (1)  to  soften  and  dissolve  the  food  so  that 
it  can   be    masticated    and    swallowed.     (The    saliva   is 
mostly  water  and  hence  it  aids  in  masticating  and  swal- 
lowing.    All  food  contains  at  least  some  water) ;  (2)  to 
keep  substances  in  solution  while  moving  in  the  body ; 
(3)  to  carry  the  waste  material  out  of  the  body ;  (4)  to 
cool  the  body  by  evaporation  of  the  perspiration. 


THE    CARE   OF   THE   DIGESTIVE    ORGANS.  53 

LESSON    19. 
The  Care  of  the  Digestive  Organs. 

1.  It  is  very  important  that  we  know  how  to  care  for 
the  organs  that  are  engaged  in  the  great  work  of  prepar- 
ing the  material  which  keeps  our  bodies  in  working  con- 
dition ;  for  it  is  not  what  we  eat,  but  what  we  digest  and 
assimilate,  that  makes  us  strong  and  keeps  us  alive.     We 
may  eat  too  much  or  not  enough ;  our  food  may  be  un- 
wholesome or  improperly  selected.     The  digestive  organs 
may  be  injured  in  many  ways  and  rendered  unable  to 
perform  their  proper  work. 

2.  Quantity  of  Food.  — The  appetite,  if  not  perverted, 
is  a  very  good  guide  as  to  the  proper  quantity  of  food  to 
eat.     The  appetite  is  natural  so  long  as  the  food  is  plain 
and  we  take  sufficient  exercise  and  avoid  exposures  and 
other  causes  of  ill  health.     Indulgence  in  food  simply  to 
gratify  the  taste  for  certain  articles  will  soon  pervert  the 
appetite.     One  should  eat  from  a  natural  desire  for  food 
and  not  simply  because  a  certain  article  pleases  our  sense 
of  taste.     It  is  true  our  food  should  taste  good  to  us,  but 
it  must  be  remembered  that  the  plainest  and  simplest 
articles  of  diet  will  taste  good  if  we  have  a  real  appetite. 

The  quantity  of  food  necessary  depends  on  a  number  of 
conditions.  (1)  A  little  more  is  required  by  persons  dur- 
ing their  growing  period,  in  proportion  to  their  size,  than 
after  the  period  of  growth,  is  completed.  (2)  In  cold 
climates  and  in  winter  a  little  more  food  is  needed  than 
in  warm  climates  and  in  summer.  (3)  Persons  who  labor 
need  more  than  those  who  do  not. 

3.  Quality  of  Food.  —  (1)  Food  should  be  wholesome, 
that  is,  free  from  any  poisonous  elements.     Meats  which 


54  PHYSIOLOGY    FOR  BEGINNERS. 

are  "tainted"  frequently  contain  poisonous  substances 
produced  in  the  decay  of  the  flesh.  Stale  and  partly 
decayed  vegetables  are  also  unwholesome  for  the  same 
reason.  Food  from  plants  and  animals  affected  with  dis- 
ease is  usually  unwholesome.  (2)  Food  should  not  be  too 
highly  concentrated.  A  certain  amount  of  bulk  is  neces- 
sary, as  the  stomach  acts  better  on  a  large  than  on  a 
small  quantity ;  and  a  certain  amount  of  mere  waste  mat- 
ter stimulates  the  stomach  and  intestines  and  increases 
their  action.  (3)  Food  should  not  be  too  easy  of  diges- 
tion, as  then  the  stomach  does  not  have  sufficient  exer- 
cise ;  nor  too  difficult,  as  then  it  is  overworked.  (4)  Food 
should  contain  a  proper  portion  of  heat-making  and  tissue- 
making  elements.  In  winter  we  should  eat  starchy  and 
sweet  foods  and  more  fat ;  in  summer,  more  acid  fruits  and 
lean  meats  and  soups.  (5)  A  proper  mixture  of  animal 
and  vegetable  food  is,  perhaps,  the  best,  although  there 
are  some  who  think  a  purely  vegetable  diet  is  to  be 
preferred. 

• 

4.  Cooking.  — Cooking  renders  many  kinds  of  food 
more  easy  of  digestion  by  softening  it  and  making  it 
more  soluble.  It  also  improves  the  flavor.  Many  kinds 
of  meat,  especially  pork,  are  apt  to  contain  the  germs  of 
certain  parasites,  or  worm-like  animals,  which,  if  taken 
into  the  stomach,  grow  and  multiply  and  produce  some- 
times fatal  disease.  Heating  meat  to  the  boiling  point 
destroys  these  germs  and  renders  it  safe.  Never  eat  raw 
meat  of  any  kind.  Frying  meats,  as  ordinarily  practiced, 
renders  them  indigestible.  If  the  fat  be  very  hot  when 
the  meat  is  put  in,  it  does  not  penetrate  the  meat  and 
does  not  injure  it. 

Warm  food  is  usually  better  than  cold  food,  as  it  cor- 


THE    CARE    OF    THE    DIGESTIVE    ORGANS.  55 

responds  more  nearly  with  the  natural  temperature  of  the 
stomach. 

5.  Variety  of  Food.  —  The  system  seems  to  demand  a 
variety  of  food.     The  same  kind  of  food,  however  nutri- 
tious, when  prepared  exactly  the  same  way  soon  becomes 
unpalatable. 

6.  Regularity  in  Eating.  —  The  stomach  tends  to  act 
periodically,  that  is,  at  regular  recurring  periods  it  is  in 
better  condition  for  digesting  food.     Meals  at  regular  in- 
tervals of  time  seem  to  be  better  than  when  not  regular, 
as  the  sensation  of  hunger  will  recur  at  about  the  same 
time,  and  if  not  gratified  at  the  time  it  passes  away,  and 
then,  if  we  eat,  we  lose  much  of  the  proper  enjoyment  of 
the  food.     The  appetite  is  not  then  a  good  guide,  and  we 
may  eat  too  much  or  too  little. 

7.  Eating   between   Meals.  —  This   is   a   bad  practice. 
The  stomach  needs  rest,  and  when  food  is  taken  too  often 
it  is  constantly  in  exercise.     Persons  who  are  continually 
eating  nuts,  candy,  or  fruit  between  meals  are  very  apt  to 
have  dyspepsia  in  time. 

8.  Take    Plenty   of    Time    to    Eat.  —  One   should   eat 
slowly,  taking   time  to  masticate  the  food  thoroughly. 
This  gives  the  salivary  and  gastric  glands  also  time  to 
secrete  the  proper  amount  of  fluid.     Lively  conversation 
and  humor  at  the  table  favors  digestion  and  prevents  eat- 
ing too  rapidly. 

9.  Warm  and  Cold  Drinks.  —  Warm  drinks  are  gener- 
ally favorable  to   the   action   of   the   stomach.     Ice-cold 
drinks  lower  the  temperature  of  the  stomach  too  much  and 
ought  not  to  be  indulged  in  to  any  great  extent. 


56  PHYSIOLOGY    FOR   BEGINNERS. 

10.  The   Use   of   Condiments.  —  Condiments   are    such 
substances   as   salt,  spices,   and  vinegar,  which  are  not 
foods,  but   frequently  render   foods  more  palatable.     If 
indulged  in  to  any  great  extent,  they  are  apt  to  inflame 
the  coats  of  the  stomach  and  produce  dyspepsia.    Children 
especially  should  not  eat  their  food  highly  seasoned. 

11.  Fluids    at    Meals.  —  It   is   frequently  stated  that 
much  fluid  taken  with  the  food  retards  digestion  by  dilut- 
ing the  gastric  juice,  but  there  is  no  good  reason  for 
supposing  them  injurious.     One  should  use  proper  judg- 
ment, of  course,  as  an  excessive  quantity  would  be  injuri- 
ous.    It  is  an  almost  universal  custom  to  drink  something 
at  meals. 

12.  The   Use   of   Tea,    Coffee,   and    Chocolate.  —  These 
drinks    have    but   little   effect   directly  on    the  digestive 
organs,  but  when  used  in  excessive  quantities  they  pro- 
duce an  injurious  effect  on  the  nervous  system,  especially 
in  some  persons,  and  thus  they  indirectly  affect  digestion. 
Young  persons  do  not  need  such  drinks,  and  they  are  fre- 
quently injurious  during  the  growing  period  of  life.     Milk 
and  water  should  be  the  only  drinks  for  young  people. 

13.  Tobacco.  —  The  use  of  tobacco,  either  by  smoking 
or  chewing,  frequently  causes  dyspepsia  of  the  worst  form. 
In  chewing  tobacco  the  salivary  glands  are  unduly  ex- 
cited, and  the  saliva  thus  produced  is  thrown  away.     The 
result  is  a  weakening  of  the  glands.     Acting  through  the 
nervous  system,  tobacco  frequently  produces  very  injuri- 
ous  effects   on  the   organs   of  circulation  and   digestion. 
Physicians  all  agree  that  tobacco  is  very  injurious  to  the 
young. 

14.  Alcohol  and  Digestion.  —  Alcohol  is  not  a  food,  but 
a  poison,  in  the  true  sense  of  that  word.     Small  quantities 


REVIEW    OF    THE    DIGESTIVE    SYSTEM.  57 

well  diluted,  as  in  weak  wines  and  in  beer  and  ale,  may 
for  a  time  stimulate  a  weak  stomach  and  thus  improve 
digestion;  but  in  time  the  organs  are  weakened,  and 
more  harm  than  good  is  done  even  by  the  mildest  liquors. 
The  liver  is  especially  affected  by  a  habitual  use  of  alco- 
holic liquors.  The  livers  of  drunkards  are  often  found 
covered  with  hard  lumps,  and  sometimes  there  is  a  change 
of  a  part  of  the  substance  of  the  liver  into  fat.  Like 
tobacco,  alcohol  is  much  more  injurious  to  young  persons 
than  to  adults.  If  a  habit  of  using  either  liquor  or  tobacco 
be  formed  while  young,  it  is  next  to  impossible  to  break 
off  when  older,  and  the  habit  is  apt  to  grow  until  excessive 
quantities  are  used.  The  first  cigar  and  the  first  glass  of 
liquor  are  the  ruin  of  many  a  promising  young  man. 

15.  Care  of  the  Teeth.  —  The  teeth  are,  perhaps,  the 
least  important  of  the  digestive  organs,  and  it  is  a  pecu- 
liar fact  that  no  matter  how  well  they  be  cared  for  they 
will  sometimes  begin  to  decay  at  an  early  age.  But  in 
many  cases  the  early  decay  is  due  to  neglecting  to  keep 
them  clean.  Use  a  soft  tooth  brush  after  each  meal  with 
a  little  very  mild  soap  and  water.  Do  not  use  a  metal 
toothpick,  as  it  is  apt  to  chip  off  the  enamel.  Do  not  bite 
threads  or  crack  nuts  with  the  teeth.  Very  hot  and  very 
cold  drinks  tend  to  crack  the  enamel.  If  you  would  have  a 
sweet  breath^  keep  the  teeth  clean. 


LESSON  20. 
Review  of  the  Digestive  System. 

1.    Define  a  gland.     What  is  the  largest  gland  in  the 
body  ?     The  liver.     Locate  the  liver.     Name  the  vessels 


58  PHYSIOLOGY    FOR   BEGINNERS. 

of  the  liver.  What  vessels  carry  material  into  the  liver  ? 
The  portal  vein  and  the  hepatic  artery.  What  vessels 
carry  material  out  of  the  liver  ?  The  hepatic  veins,  the 
hepatic  duct,  and  the  lymphatics. 

2.  What   is   bile  ?     How   does   the   bile   get  into  the 
intestine?     How  does  it  get  into  the  gall-bladder  ? 

3.  Name  two  uses  of  the  liver.     What  relation  has  the 
liver  to  the  sugar  which  is  absorbed  in  the    stomach? 
Why  is  the  liver  like  a  bank  ? 

4.  Locate  the  pancreas.    What  is  the  use  of  this  gland  ? 
What  is  the  effect  of  the  pancreatic  fluid  on  food?     In 
what  respect  is  the  pancreatic  juice  like  saliva  ? 

5.  Tell  all  you  know  about  the  spleen.     (It  has  been 
taken  out  of  animals  without  any  noticeable  effect  follow- 
ing its  removal.) 

6.  Define  digestion.     What  part  of  the  digestive  proc- 
ess is    performed  in  the  mouth  ?     In  the  stomach  ?     In 
the  small  intestine  ?     What  is  the  use  of  the  "  pylorus  "  ? 

7.  What  is  chyme?     Chyle?     What  is  the   color  of 
chyle  ? 

8.  Explain  absorption.     What  kind  of  substances  can 
be  absorbed  ?     Only  those  that  are  in  a  state  of  solution, 
or,    in    other   words,    in  a  liquid   form.     What    are    the 
lacteals  ?     What    is   the    thoracic    duct  ?     What    does   it 
carry  ?     Into  what  does  it  empty  ? 

9.  Define  food.    What  are  the  two  uses  of  food  ?    What 
produces  the  heat  of  the  body  ? 

10.  What  is  meant  by  assimilation  ?     Is  it  correct  to 
say  that  what  is  a  part  of  an  apple,  an  egg,  or  a  head  of 
cabbage  to-day,  may  be  a  part  of  your  bones,  muscles,  and 
nerves  to-morrow  ? 

11.  State  whether    each  of  the  following-named  sub- 
stances is  a  heat-making  or  tissue-making  food.     Sugar, 


THE    HEART.  59 

albumen,  fibrin,  starch,  oil,  casein,  legumin.  Suppose 
you  make  a  meal  of  bread  and  butter,  do  you  get  heat- 
making  material  ?  Yes,  from  the  oil  of  the  butter  and 
from  the  starch  and  sugar  of  the  bread.  Do  you  get  any 
tissue-making  material?  Yes,  from  the  gluten  of  the 
bread. 

12.  Name  three  articles  of  food  better  suited  for  cold 
weather.     What  is  the  use  of  water  in  the  system  ? 

13.  Should  the  mere   taste  of   the  food   guide   us  in 
determining  the  quantity  we  should  eat  ?     Why  should 
a  laboring  man  eat  more  than  one  who  does  not  labor  ? 

14.  What  is  the  objection  to  eating  tainted  meat  and 
stale  or  decayed  vegetables  ? 

15.  Why  do  we  cook  food  ?     What  danger  in  eating 
raw  meat  ?     Why  is  warm  food  better  than  cold  ? 

16.  Why   should    meals    be   regular  ?      What   is   the 
objection  to  eating  between   meals  ?      Why  should  one 
eat  slowly  ? 

17.  What  can  be  said  about  warm  and  cold  drinks? 
The  use  of  spices,  salt,  and  vinegar  ? 

18.  What  of  the  effects  of  tea,  coffee,  and  chocolate, 
on  the  digestive  organs  ?     Of  tobacco  ?     Of  alcohol  ?     Is 
alcohol  a  food  ? 

19.  How  care  for  the  teeth  ? 


LESSON  21.  . 
The  Heart. 

i.  Definition.  — We  have  learned  that  the  blood  is  man- 
ufactured by  the  digestive  organs  from  the  food.  Some 
means  for  its  perfect  circulation  through  the  body  is 


60  PHYSIOLOGY    FOE    BEGINNERS. 

necessary.  The  heart  and  blood  vessels  are  the  means. 
The  heart  is  a  muscular  pump,  which  by  its  contractions 
forces  the  blood  into  one  set  of  vessels  called  arteries  and 
draws  it  from  another  set  called  veins,  thus  producing  a 
constant  flow  from  a  central  point  to  the  remotest  parts 
of  the  body  and  back  again. 

2.  Location.  —  The  heart  lies  between  the  lungs,  the 
greater  portion  being  a  little  to  the  left  of  the  middle 
of   the    chest.      The    larger    end    points   upward,    back- 
ward, and  toward  the  right ;  the  smaller  end,  downward, 
forward,  and  toward  the  left.     The  smaller  end  can  be 
felt,  when  it  beats,  at  a  point  between  the  cartilage  of 
the  fifth  and  sixth  ribs,  a  little  to  the  left  of  the  sternum. 

3.  Size  and  Shape.  —  The  human  heart  is  about  three 
and  one  half  inches  long,  two  and  one  half  inches  thick, 
and  weighs  from  eight  to  twelve  ounces  in  a  grown  per- 
son ;  or  it  is  very  near  the  size  of  the  person's  fist.     The 
heart  of  a  hog  or  sheep  when  full-grown  is  very  nearly 
the  same  size  and  shape  of  a  human  heart. 

4.  Cavities.  —  The  heart  is  a  double  organ,  a  partition 
running  through  it  lengthwise  dividing  it  into  right  and 
left  sides.     The  right  side  pumps  impure  blood  from  the 
body  to  the  lungs,  and  the  left  side  pumps  pure  blood 
received  from  the  lungs  to  all  parts  of  the  body.     Each 
side  has   two    cavities,  the   upper   ones   called   auricles, 
which  receive  the  blood,  and  the  lower  called  ventricles, 
which  discharge  the  blood. 

5.  The  Right  Auricle.  —  This  cavity  is  a  little  larger 
than  the  left  auricle  and  has  thinner  walls.     It  receives 
the  blood  from  the  entire  body  through  two  main  tubes, 
the  superior  vena  cava,  which  brings  it  from  the  upper 


THE    HEART.  61 

part  of  the  body,  and  the  inferior  vena  cava,  which  brings 
it  from  the  lower  part  of  the  body  and  discharges  the 
blood  through  an  opening  into  the  right  ventricle.  The 
blood  which  circulates  through  the  walls  of  the  heart  itself 
is  also  returned  to  the  right  auricle  through  one  large  vein 
(the  coronary  vein)  and  a  number  of  very  small  ones. 

6.  The  Right  Ventricle.  —  This  cavity  is  the  same  size 
as  the  left  ventricle,  but  has  much  thinner  walls.     The 
blood  is  prevented  from  returning  to  the  right  auricle  by 
three  triangular  flaps  of   membrane,  hanging   from  the 
opening  and  connected  by  fibrous  cords  to  fleshy  columns 
on  the  sides  of  the  cavity  of  the  ventricle.    The  blood  can 
pass  through  these  flaps,  but  when  the  ventricle  contracts 
it  cannot  go  back,  as  the  blood  gets  behind  them  and  they 
are  pushed  together.     This  arrangement  is  called  the  tri- 
cus-pid  (three-pointed)  valve.     When   the  ventricle  con- 
tracts, the    blood  is  forced   into    the  pulmonary  artery 
and  through  it  to  the  lungs.     It  is  prevented  from  return- 
ing by  three  pockets  of  membrane,  which  open  toward  the 
artery.     When  the  blood  passes  from  the  ventricle,  they 
offer  no  hindrance ;  but  it  is  prevented  from  returning  by 
getting  into  the  pockets  and  bulging  them  out  so  as  to 
close  the  opening.     These  pockets  are  called  the  sem-i-lu- 
nar  (half  moon)  valves. 

7.  The  Left  Auricle.  —  This  cavity  has  four  openings 
for  as  many  pulmonary  veins,  which  return  the  blood  from 
the  lungs,  and  one  opening,  through  which  the  blood  passes 
into  the  left  ventricle. 

8.  The  Left  Ventricle. — This  is  similar  to  the  right 
ventricle.      The  blood  corning  from  the  left  auricle  is  pre- 
vented from  returning  by  the  mi-tral  valve  (so  called  from 


62 


PHYSIOLOGY    FOR    BEGINNERS. 


its  resemblance  to  a  bishop's  cap  or  "  miter  ").  This  valve 
consists  of  two  flaps  of  membrane  similar  to  those  which 
compose  the  tricuspid  valves.  The  contraction  of  the 
ventricle  sends  the  blood  into  the  a-or-ta,  or  great  trunk 
of  the  arterial  system,  from  which  it  is  distributed  through- 
out the  body.  The  entrance  to  the  aorta  is  guarded  by  a 
set  of  semilunar  valves,  like  those  on  the  right  side  of 
the  heart. 


9.  The  Covering  of  the  Heart.  —  The  heart  is  enclosed 
in  a  bag  of  fibrous  membrane.  This  bag  is  lined  with  a 
serous  membrane,  which  turns  and  covers  the  heart  itself. 
The  serous  membrane  secretes  a  fluid  which  keeps  the  sur- 
faces moist  and  prevents  friction.  When  this  fluid  is 
greatly  increased  in  quantity,  as  is  the  case  in  some 

diseases,  there  is  said  to  be 
"  dropsy  of  the  heart."  The 
fibrous  bag  is  called  the  per-i- 
car-di-um  (around  the  heart). 

10.  The  Structure  of  the 
Heart.  —  The  heart  consists 
of  muscular  fibers  interlaced 
and  attached  to  fibrous  rings, 
which  surround  the  openings 
i'  between  the  auricles  and  ven- 
tricles and  the  blood  vessels. 
The  cavities  are  lined  with 
a  serous  membrane,  which  is 
a  continuation  of  the  inner 
coat  of  the  blood  vessels. 

This  membrane  is  called  the  en-do-car-di-um  (within  the 

heart). 


FIG.  9. 


THE    HEART.  63 

11.  The  Movements  of  the  Heart.  — We  say  the  heart 
beats,  or  pulsates.    This  consists  of  a  kind  of  wave  motion, 
beginning  with  the  auricles  and  ending  with  the  ventri- 
cles.    The  muscular  walls  of  the  auricles  first  contract 
and  force  the  blood  into  the  ventricles,  which  are  at  that 
instant  relaxed.     Then  the  ventricles  contract,  and  as  the 
blood  cannot  go  back  into  the  auricles,  being  prevented 
by  the  valves,  it  is  forced  into  the  arteries.     While  the 
ventricles  are  contracting,  the  auricles  are  relaxed  and 
filled  with  blood  from  the  veins.     The  heart  is  suspended 
by  the  large  blood  vessels  coming  from  its  base,  or  upper 
end ;  but  the  lower  end  is  free  to  move,  and  when  the 
ventricles  contract  it  is  tilted  so  that  it  strikes  the  wall  of 
the  chest. 

12.  Rate  of  Pulsation.  — The  heart  in  a  grown  person 
beats,  on  an  average,  70  times  in  a  minute.     In  the  new- 
born babe  it  beats  from  130  to  140  times  per  minute, 
the  rate  gradually  becoming   less  until  old   age.      The 
heart  beats  a  little  faster  in  women  than  in  men,  faster 
during  exercise  and  just  after  eating,  and  slower  during 
sleep.      Different  conditions  of  disease  cause  variations. 
It  has  been  known  to  beat  but  20  times  in  a  minute, 
and  again  as  fast  as  160  times  per  minute  in  the  grown 
person. 

13.  Sounds  of  the  Heart.  —  If  the  ear  be  placed  over 
the  chest,  two  distinct  sounds  may  be  heard,  caused  by 
the  pulsation  of  the  heart.     One  sound,  which  is  called  the 
first  sound,  is  dull  and  caused  by  the  muscular  contrac- 
tion of  the  ventricles.     The  other,  called  the  second  sound, 
is  sharper  and  is  caused  by  the  shutting  of  the  seinilunar 
valves.     Between  the  second  and  first  sounds  is  an  inter- 
val of  silence.     The  physician  uses  an  instrument  called 


64  PHYSIOLOGY  FOR  BEGINNERS. 

the  steth-o-scope,  which  magnifies  these  sounds.  He  is 
thus  enabled  to  discover  diseases  of  the  heart,  for  when- 
ever there  is  any  unnatural  sound  there  is  something 
wrong  in  the  structure  of  the  heart. 


LESSON  22. 
The  Blood  Vessels. 

1 .  Definition.  —  The  blood  vessels  are  a  set  of  elastic 
pipes,  or  tubes,  which  permit  the  blood  to  pass  to  every 
part  of  the  body  from  the  heart  and  back  again  to  the 
heart.     There  are  three  kinds  of  blood  vessels,  arteries, 
veins,  and  capillaries.     The  arteries  carry  blood  away  from 
the  heart.     The  veins  carry  blood  to  the  heart.     The  cap- 
illaries are  the  fine  tubes  which  connect  the  arteries  to 
the  veins  throughout  the  tissues  of  the  body. 

2.  The  A-or-ta. — All  of  the  arteries  are  branches  of 
one  great  artery,  which  is  called  the  a-or-ta.     It  is  about 
one  inch  in  diameter,  and  commences  at  the  upper  part  of 
the  left  ventricle,  curves  over  backward  and  toward  the 
left,  then  descends  along  the  left  side  of  the  spinal  column 
as  far  as  the  fourth  lumbar  vertebra,  where  it  divides  to 
form  the  right  and  left  common  iliac  arteries.     A  number 
of  branches  are  given  off  along  its  course,  these  branches 
supplying  the  trunk  of  the  body  and  the  thoracic  and 
abdominal  organs  with  blood. 

3.  Some   of   the   Principal   Arteries.  —  It  would  be  a 
great  task  to  learn  the  names  of  all  the  arteries  in  the 
body,  and  unless  you  were  a  surgeon  it  would  not  be  of 
importance  to  know  them.     But  it  will  be  interesting  to 


THE    BLOOD    VESSELS.  65 

know  the  names  of  a  few  of  the  larger  ones.  First,  the 
right  and  left  coronary  arteries  supply  the  walls  of  the 
heart  itself  with  blood.  At  the  right  of  the  curve  of 
the  aorta  a  short  artery  branches  off,  called  the  in-nom-i- 
nate  artery.  This  divides  into  the  right  ca-rot-id  and 
right  sub-cla-vi-an  arteries,  the  former  supplying  the  right 
side  of  the  head,  and  the  latter  the  right  shoulder  and 
arm.  The  left  carotid  and  left  subclavian  arteries  branch 
off  separately  from  the  aorta. 

The  gastric  artery  supplies  the  stomach,  the  hepatic  the 
liver,  and  the  splenic  the  spleen.  These  three  are  branches 
of  a  short  trunk  which  comes  off  from  the  aorta  below 
the  heart.  The  superior  and  inferior  mes-en-ter-ic  arteries 
supply  the  intestines.  The  aorta  divides,  as  we  have 
before  stated,  into  the  right  and  left  common  iliac  arteries. 
These  divide  to  form  internal  and  external  iliac  arteries, 
the  former  supplying  the  parts  about  the  pelvis,  and  the 
latter  the  lower  limb.  The  external  iliac  takes  the  name 
of  the  femoral  artery  on  the  thigh. 

4.  Position  of  the  Arteries.  —  The  arteries  are  gener- 
ally placed  deep  in  the  tissues  of  the  body.     Where  they 
do  come  near  the  surface,  it  is  always  in  a  place  that  is 
naturally  protected,  as  in  the  hollows  formed  by  the  angles 
of  the  limbs,  the  hollow  of  the  neck,  and  similar  places. 
Thus,  you  may  feel  the  carotid  artery  pulsate  in  the  side 
of  the  neck,  the  temporal  in  the  hollow  in  front  of  the  ear, 
the  pop-lit-e-al  behind   the   knee,    and   others   in   similar 
protected  positions. 

5.  Structure  of  the  Arteries.  —  The  arteries  are  elastic 
tubes  varying   in  size  from  nearly  an  inch  in  diameter 
down  to  a  thickness  but  a  little  greater  than  a  hair.     The 
walls  are  composed  of  three  layers,  or  coats.     The  outer 


66 


PHYSIOLOGY    FOR    BEGINNERS. 


and  middle  coats  are  composed  of  fibrous  tissue,  the  latter 
containing  muscular  fibers,  which  are  proportionally  more 
abundant  in  the  small  arteries.  The  inner  coat  is  a  serous 
membrane,  very  smooth  and  thin.  The  outer  coat  is  the 
strongest.  If  a  string  be  tied  very  tightly  around  an  ar- 
tery, it  will  sever  the  middle  and  inner  coat,  leaving  the 
outer  coat  uninjured.  The  outer  coat  is  for  strength,  the 
middle  for  elasticity  and  contraction  ;  and  the  inner  makes 
a  smooth  surface  for  the  flow  of  the  blood. 

6.  Branching  of  the  Arteries. 
— When  an  artery  divides  to 
form  two,  each  branch  is 
smaller  than  the  main  one,  but 
both  taken  together  are  larger 
than  the  main  artery ;  so  that 
the  combined  area  of  all  the 
small  arteries  is  much  greater 
than  the  aorta,  or  main  trunk. 
If  this  were  not  the  case,  the 
heart  would  have  an  im- 
mensely greater  work  to  per- 
form, for  the  friction  would 
be  greater.  In  many  places 
the  branches  from  a  main 
artery  join  with  other  branches 
from  the  same  artery.  This  is  called  an-as-to-mos-ing, 
a  word  which  literally  means  "mouth  to  mouth."  The 
surgeon  is  frequently  required  to  tie  a  large  artery,  and 
in  such  cases  these  anastomosing  branches  carry  the 
blood  around  and  keep  up  the  circulation. 

7.   The  Veins. — These  vessels  carry  back  to  the  heart  the 
blood  that  has  been  carried  out  through  the  system  by  the 


FIG.  10. 


THE    BLOOD    VESSELS. 


67 


arteries.  They  are  more  numerous,  but  softer  and  weaker 
than  the  arteries.  They  are  but  slightly  elastic,  and  when 
not  filled  with  blood  the  walls  collapse,  or  fall  together. 
The  deep  veins  accompany  the  arteries,  there  being  gener- 


FlG.    11. 


ally  two  to  each  artery,  and  take  similar  names.  The 
superficial  veins  lie  just  beneath  the  skin,  are  smaller  and 
very  numerous.  You  may  see  on  the  back  of  your  hand 
the  ridges  made  by  these  superficial  veins.  You  may  by 


68 


PHYSIOLOGY    FOR    BEGINNERS. 


pressure  with  your  finger  stop  the  flow  of  blood  in  one  of 
them. 

8.   Structure  of  Veins.  —  Like  arteries,  the  walls  are 
composed  of  three  coats.     The  middle  coat  is  very  weak 


FIG.  12. 


and  has  a  very  few  muscular  fibers.     The  inner  layer  con- 
tains folds  in  many  places,  called  valves.     These  valves 


THE    BLOOD    VESSELS.  69 

permit  the  blood  to  pass  in  a  direction  toward  the  heart, 
but  prevent  its  flow  in  the  opposite  direction. 

9.  The  Capillaries.  —  The  arteries  get  smaller  and 
smaller  and  more  numerous  as  they  approach  the  tissues 
of  the  body  which  they  supply  with  blood,  and  when  not 
more  than  j^vs  of  an  inch  in  diameter  they  take  the  name 
of  capillaries,  from  a  Latin  word  meaning  "  hair."  They 
are,  indeed,  smaller  than  hairs,  but  what  they  lack  in  size 
is  made  up  in  numbers.  They  are  spread  throughout  the 
body  so  thickly  that  there  are  but  few  points  on  the 
body  where  a  fine  needle,  if  inserted,  would  not  puncture 
one  or  more  of  them.  There  are  none  in  the  nails,  hair, 
epidermis,  and  cornea  of  the  eye.  They  consist  of  a 
single  wall  of  transparent  membrane,  through  which 
liquids  and  gases  freely  pass.  You  may  £hen  ask,  Why 
does  not  the  blood  all  leak  out  ?  There  are  two  answers 
to  this  question.  First,  the  blood  is  not  a  perfect  liquid, 
being  a  liquid  with  myriads  of  solid  little  bodies  floating 
in  it.  Second,  the  liquid  part  of  the  blood  does  leak 
through  this  membrane  and  thus  furnishes  material  for 
building  the  tissues.  The  torn  down  tissues,  also,  in  part 
pass  back  into  the  blood  vessels  through  these  capillary 
walls.  The  blood  loses  certain  elements  in  passing  from 
the  arteries  to  the  veins  through  the  capillaries,  and  gains 
other  elements.  This  change  is  shown  by  the  difference 
of  color.  The  blood  in  the  arteries  is  a  bright  scarlet, 
and  that  in  the  veins  is  dark  red.  This  is  true  of  the 
vessels  in  general,  but  in  the  lungs  it  is  reversed.  The 
pulmonary  artery  carries  dark  blood,  and  after  it  has 
passed  through  the  capillaries  of  the  lungs,  it  appears  in 
the  pulmonary  veins  bright  scarlet.  We  say  the  blood 
is  purified  by  passing  through  the  lungs  and  absorbing 
oxygen  from  the  air.  » 


70  PHYSIOLOGY  FOR  BEGINNERS. 

LESSON   23. 
The  Blood  and  How  it  Circulates. 

1.  Quantity  of  Blood. — In  a  full-grown  human  body 
there  are  about  two  and  a  half  gallons  of  blood,  or,  in 
other  words,  about  one-eighth  of  the  weight  of  the  body. 

2.  Properties  of  Blood.  — Blood  is  a  little  heavier  than 
water,  is  salty  to  taste,  and  has  an  odor  differing  from 
that  of  any  other  substance.     Its  color,  as  we  learned  in 
the  last  lesson,  is  bright  scarlet  in  the  systemic  arteries 
and  darker  in  the  systemic  veins.    In  a  few  minutes  after 
it  leaves  the  body,  it  undergoes  a  peculiar  change  called 
co-ag-u-la-tion,  or  dotting.    It  separates  into  two  portions, 
one  thick,  like  jelly,  and  the  other  thin,  like  water.     The 
jelly-like  portion  is  much  greater  in  quantity. 

3.  Composition  of  Fresh  Blood. — To  the  unaided  eye 
the  blood  appears  as  a  simple  red  liquid,  not  unlike  red 
ink.     But  if  a  little  be  spread  thinly  on  a  glass  slide  and 
examined  with  a  good  microscope,   a  number    of    little 
round  bodies  are  seen  floating  in  a  clear  liquid.     These 
little  bodies  are  called  blood  cor-pus-cles  (little  bodies),  or 
blood   cells.      The  majority  of  them  appear  faintly  red 
or  yellowish  when  seen  singly,  but  when  a  number  are 
heaped  together,  they  have  the  deeper  red  color  of  the 
blood.     Here  and  there  among  these  red  corpuscles  may 
be  seen  some   that   are   white   or  nearly  colorless.     The 
colorless  liquid  in  which  the    corpuscles   float   is  called 
plasma,   or   liquor  sanguinis.      It    is    composed    of    albu- 
minous matter,  mineral  salts,  and  water.     The  red  cor- 
puscles contain  a  substance  called  hem-o-glo-bin.     It  con- 
tains iron  and  gives  the  blood  its  red  color. 


THE  BLOOD  AND  HOW  IT  CIRCULATES.        71 

4.  Composition  of  Coagulated  Blood.  —  The  watery  part 
of  clotted  blood  is  called  se-rum.  The  jelly-like  part  is 
called  the  co-ag-u-lum,  or  clot.  It  consists  of  a  stringy  sub- 
stance called  fibrin  and  corpuscles,  which  seem  to  be  simply 
entangled  in  it.  By  taking  a  portion  of  clot  and  shaking 
in  a  bottle  of  clean  water,  then  pouring  off  the  red  liquid 
and  repeating  this  many  times,  a  white  stringy  substance 
is  left.  This  is  the  fibrin.  The  water  is  reddened  by  the 
corpuscles,  which  are  dissolved  in  it. 


FIG.  13. 

5.  Importance  of  Coagulation.  —  The  cause  of  coagula- 
tion is  not  certainly  known,  but  its  importance  to  the 
animal  is  undoubted.  It  is  nature's  method  of  stopping 
bleeding.  The  blood  by  coagulating  closes  the  severed 
vessels,  and  thus  stops  the  flow  from  the  wound.  Unless 
a  very  large  blood  vessel  be  severed,  there  is  seldom  a  case 
of  bleeding  to  death  either  in  man  or  animals.  In  birds 
coagulation  takes  place  almost  instantly  after  leaving  the 
blood  vessels. 


72  PHYSIOLOGY    FOE    BEGINNERS. 

6.  The  Use  of  the  Corpuscles.  — The  red  corpuscles  carry 
oxygen  from  the  lungs  to  the  tissues  of  the  body.     The 
oxygen  is  a  part  of  the  air  we  breathe,  and  is  essential  to 
all  living  things.     The  hemoglobin  of  the  red  corpuscles 
unites  with  the  oxygen,  and  in  this  manner  the  latter  is 
carried  to  the  tissues  of  the  body.    The  white  corpuscles  are 
probably  concerned  in  the  growth  and  repair  of  the  tissues. 

7.  The  Course  of  the  Blood  in  the  Body.  —  Starting  with 
the  capillaries  throughout  the  tissues  of  the  body,  let  us 
trace  the  blood  in  its  ceaseless  round.     From  the  capillaries 
it  flows  into  the  small  branches  of  the  veins,  from  these 
into  larger,  and  again  into  larger  branches,  until  the  heart 
is  reached  by  two  main  trunks.     These  empty  the  blood 
into  the  main  auricle.     From  the  right  auricle  it  flows  into 
the  right  ventricle.      From  the  right  ventricle  into  the 
pulmonary  artery,  and  through  its  numerous  branches  to 
the  capillaries  of  the  lungs.     Thus  far  it  is  dark,  or  venous 
blood.     In  the  capillaries  of  the  lungs  it  receives  oxygen 
and  gives  up  carbon  dioxide,  and  appears  in  the  pulmonary 
veins  as  bright  red,  or  arterial  blood.     The  pulmonary 
veins  empty  it  into  the  left  auricle.     From  here  it  passes 
to  the  left  ventricle.     From  the  left  ventricle  it  is  forced 
into  the  aorta,  and  from  thence  into  all  its  branches  and 
branches  of  branches,  until  the  capillaries  of  the  body  are 
again  reached. 

A  kind  of  special  circulation  exists  in  the  liver.  All  the 
blood  which  has  been  distributed  to  the  stomach,  spleen, 
and  intestines  is  gathered  up  by  veins  which  unite  to  form 
the  por-tal  vein,  which  enters  the  liver,  and  there  divides 
again  into  many  branches.  This  blood  is  then  gathered  up 
by  the  hepatic  veins  in  the  liver,  and  emptied  into  the 
inferior  vena  cava,  or  lower  great  trunk  of  the  venous 


THE    BLOOD    AND    HOW    IT    CIRCULATES.  73 

system.     This  course    of  the  blood  is   called   the  portal 
circulation. 

8.  Cause  of  Circulation.  —  The  main  cause  of  circulation 
is  the  pumping  force  of  the  heart.  This  force  is  felt  in  the 
smallest  arteries  as  a  pulsation,  or  beat.  Every  time  the 
heart  beats  there  is  a  pulsation  in  all  the  arteries. 
Although  the  pulsation  is  not  usually  to  be  perceived  in 
the  capillaries  and  veins,  yet  the  pressure  produced  by  the 
pumping  of  the  heart  is  sufficient  to  send  the  blood 
through  the  capillaries  into  the  veins.  Muscular  contrac- 
tion in  the  walls  of  the  arteries,  the  elasticity  of  the 


FIG.  14. 

arteries,  the  pressure  of  the  moving  muscles  of  the  body 
upon  the  veins,  aided  by  their  valves,  all  have  their  effect 
in  aiding  the  action  of  the  heart. 

9.  The  '  '  Pulse-writer. ' '  —  The  physician  feels  the  pulse 
of  the  patient  to  ascertain  how  the  heart  is  beating,  and  to 
know  the  force  of  the  circulating  blood  current,  for  these 
are  important  facts  in  studying  the  nature  of  the  disease. 
An  instrument  has  been  invented  which  writes  down  the 
condition  of  the  circulatory  system.  It  consists  of  a  lever 
so  arranged  that  the  pulse  in  the  wrist  may  move  it  up  and 
down  freely.  At  the  same  time  the  point  of  the  lever  is 
made  to  press  upon  a  piece  of  smoked  paper,  which  is  made 


74  PHYSIOLOGY    FOR    BEGINNERS. 

to  move  along  at  a  regular  rate  by  clockwork.  In  this 
way  the  lever  is  made  to  write  a  wavy  line  as  shown  in  the 
picture,  which  is  an  exact  copy  of  the  writing  made  by  the 
pulse  of  the  author  of  this  book.  Variations  in  these 
curves  show  variations  in  force,  frequency,  and  regularity 
of  the  heart-beats,  and  the  degree  of  resistance  in  the 
arteries,  points  of  great  value  to  the  physician. 

10.  Rate  of  Circulation.  — A  given  portion  of  blood 
may  make  the  complete  circuit  of  the  body ;  that  is,  from 
veins  to  right  side  of  heart,  to  lungs,  back  to  left  side  of 
heart,  to  the  arteries,  and  thence  through  the  capillaries  to 
the  veins  again  from  whence  it  started,  in  the  short  space 
of  twenty-four  seconds.  It  is  estimated  that  the  entire 
amount  of  blood  in  a  man's  body  makes  a  complete  circuit 
every  two  minutes. 


LESSON  24. 
The  Lymphatics. 

1.  What   are   Lymphatics?  —  They   are   a   system   of 
vessels  and  glands  which  aid  the  circulatory  system.     The 
vessels  carry  a  fluid  called  lymph. 

2.  Lymphatic   Vessels. — These   are   minute,  delicate, 
transparent  tubes,  with   valves  in   their  interior,  giving 
them  a  beaded  or  knotted  appearance.     They  are  found  in 
nearly  every  part  of  the  body,  being  more  numerous  than 
the  veins. 

3.  Thoracic  Duct  and  Right  Lymphatic  Duct.  —  All  the 

lymphatic  vessels  of  the  body,  except  those  of  the  right 


THE    LYMPHATICS.  75 

side  of  the  head,  neck  and  chest,  right  arm,  lung  and 
upper  surface  of  the  liver,  unite  and  empty  their  contents 
into  one  common  trunk  —  the  thoracic  duct.  It  lies  along 
the  front  of  the  spinal  column,  extending  from  the  second 
lumbar  vertebra  to  the  seventh  cervicle.  It  is  about  18 
inches  long,  and  one-quarter  of  an  inch  thick.  The  lower 
end  is  a  kind  of  bag  called  the  receptacle  of  the  chyle,  and 
the  upper  end  empties  into  the  left  subclavian  vein.  All 
those  lymphatic  vessels  which  do  not  empty  into  the 
thoracic  duct  form  a  common  duct  about  one  inch  in  length, 
called  the  right  lymphatic  duct.  It  empties  into  the  right 
subclavian  vein. 

4.  The  Lacteals.  —  Those  lymphatics  which  terminate 
in  the  villi  of  the  intestines  (see  Lesson  14)  are  called 
lacteals,  from  a  Latin  word  meaning  milk.,  because  during 
digestion  they  are  filled  with  a  milk-white  fluid,  the  chyle. 
They  empty  the  chyle  into  the    thoracic  duct,  where  it 
mingles  with  the  lymph,  and  finally  enters  the  general 
blood  current. 

5.  The   Lymphatic   Glands.  —  These  are  small  bodies, 
varying  in  size  from  that  of  a  grain  of  wheat  to  the  size  of 
an  almond.     They  are  found  in  various  parts  of  the  body 
in  the  course  of  the  lymphatic  vessels.     They  are  especially 
numerous  just  beneath  the  skin  under  the  arms,  in  the 
side    of  the   neck,   and   in   the   groin.     They    sometimes 
become  swollen  when  there  is  a  wound  near  them,  and 
often  are  enlarged  in  scrofulous  persons.     A    lymphatic 
vessel  passes  into  each  one,  divides  into  branches,  which 
unite  again  as  they  pass  out.     Their  use  is  not  certainly 
known. 

6.  Uses  of  the  Lymphatics.  —  As  we  have  learned,  the 
tissues  are  constantly  being  torn  down  and  built  up  anew 


76  PHYSIOLOGY    FOR    BEGINNERS. 

by  the  blood.  The  plasma  of  the  blood  passes  through  the 
walls  of  the  capillaries,  and  is  used  in  forming  new  cells. 
The  material  of  the  old  cells  is  removed  in  part  by  flowing 
back  again  into  the  capillaries.  There  is  thus  a  current  set- 
ting both  ways,  one  out  of  the  blood  vessels  into  the  tissues, 
the  other  into  the  blood  vessels.  But  wherever  there  are 
capillaries  there  are  lymphatics,  and  it  is  supposed  that 
when  there  is  more  plasma  passed  through  the  capillaries 
than  is  necessary  for  building  and  rebuilding  the  tissues,  it 
is  taken  in  by  the  lymphatics  and  thus  returned  to  the 
blood.  Probably  a  part  of  the  waste  material  is  also 
carried  away  by  the  lymphatics.  The  lymphatic  vessels 
then  seem  to  be  an  aid  to  the  circulatory  system. 


LESSON  25. 
How  to  Care  for  the  Circulatory  System. 

i.  Effects  of  Cold  and  Heat.  —  Cold  temporarily  in- 
creases the  circulation,  but,  if  continued,  checks  it  unless 
counterbalanced  by  exercise  and  stimulants,  which  for  a 
short  time  may  keep  it  up.  Heat  increases  the  circulation, 
but  when  too  great  lessens  it.  All  extremes  of  cold  and 
heat  are  injurious,  and  one  should  avoid  exposure  to  extreme 
conditions  as  much  as  possible.  Comfortable  clothing  and 
shelter  tend  to  prolong  life.  Coldness  of  feet  and  hands 
is  generally  due  to  imperfect  circulation  of  the  blood  to  the 
extremities,  and  this  deficiency  of  circulation  is  frequently 
brought  on  by  exposure  of  these  parts  to  the  cold  in  the 
first  place.  The  feet  especially  should  be  kept  warm  and 
dry. 


HOW   TO    CARE   FOB   THE    CIRCULATORY    SYSTEM.         77 

2.  Exercise  and  Circulation.  —  Place  your  finger  on  your 
wrist  and  count  the  pulsations  of  the  radial  artery  for  a 
minute    or   two.     Then   exercise   vigorously   for   several 
minutes,  and  count  again.     You  will  observe  an  increase 
in  the  number  of  pulsations  per  minute.     The  heart  beats 
more  rapidly  during  exercise,  and  the  blood  is  sent  more 
freely  to  all  parts  of  the  body.     The  movements  of  the 
muscles  also  help  the  blood  to  move  in  the  veins,  and  the 
waste  and  repair  of  the  tissues  goes  on  more  rapidly,  thus 
creating  a   demand   for   more   blood    in    the    capillaries. 
When  the  feet  begin  to  feel  cold  a  vigorous  and  constant 
working  of  the  toes  will  soon  make  them  warm,  because  of 
the  increased  amount  of  blood  sent  to  them.     Severe  and 
long-continued  exercise  may  cause  sudden  failure  of  the 
heart  or  rupture  of  a  blood  vessel. 

3.  Effects  of  Nervous  Shocks  on  the  Circulation.  —  The 

circulation  of  the  blood  is  controlled  by  the  nervous 
system,  and  any  cause  which  over-excites  or  disturbs  the 
nerves  has  an  injurious  effect  on  the  heart  and  blood 
vessels.  Strong  emotions,  as  fear,  anger,  and  grief,  cause 
irregular  action  of  the  heart,  and  consequently  of  the  blood 
vessels.  Every  one  knows  how  fear  causes  paleness,  and 
embarrassment  and  anger  cause  blushing  or  redness  of 
the  face.  This  is  due  to  the  nerves  causing  contractions 
and  relaxations  of  the  muscular  fibers  of  the  smaller 
arteries.  The  cause  of  nervous  shocks  and  excitements  can 
many  times  be  avoided.  It  is  physiologically  wrong  to 
frighten  people,  and  giving  way  to  fits  of  anger  is  at  the 
expense  of  injury  to  the  circulatory  system.  The  lives  of 
politicians  and  men  in  public  life  are  often  shortened  by  the 
excitement  under  which  they  live. 


78  PHYSIOLOGY    FOR    BEGINNERS. 

4.  Bleeding  from  Veins  and  Arteries.  —  When  a  vein  is 
severed  the,  blood  flows  in  a  steady  stream  and  is  a  little 
darker  in   appearance ;  when   an   artery  is  severed  the 
blood  flows  in  spurts  or  jets  and  is  brighter  in  color.     As 
the  bloods  flows  towards  the  heart  in  the  veins,  if  the 
bleeding  be  considerable  it  should  be  stopped  by  a  bandage 
placed  on  the  side  of  the  wound  farthest  from  the  heart. 
As  the  blood  in  the  arteries  is  flowing/rom  the  heart,  the 
bandage  should  be  placed  on  the  side  nearest  the  heart. 
No  time  should  be  lost  in  case  the  blood  flows  in  jets,  as 
a  great  and  perhaps  serious  loss  of  blood  will  soon  take 

place  from  an  ar- 
tery. A  handker- 
chief, or  towel  tied 
loosely  around  the 
limb  and  twisted 
with  a  stick,  as 

shown  in  the  picture,  will  quickly  arrest  the  bleeding  until 
a  surgeon  can  be  called.  In  case  of  a  large  artery  the  sur- 
geon will  be  obliged  to  find  the  severed  ends  of  the  artery 
and  tie  them. 

5.  Alcohol  and  the   Circulatory    Organs. — Alcohol   at 
first  causes  the   heart   to   beat  more   rapidly  and   with 
greater  force,  sending  more  blood  to  the  surface  of  the 
body.     This  causes  a  sensation  of  warmth  and  in  cold 
weather  seems  agreeable,  and  it  is  thought  by  many  to 
be  very  beneficial.     But  a  great  mistake  is  made.     The 
blood  being  sent  to  the   surface  soon   loses   its  heat  by 
radiation  and  evaporation  from  the  skin,  and  the  person 
thus  rapidly  losing  the  animal  heat  of  the  body  is  less 
able   to  resist  external  cold.     The  experience  of  travelers 
in  cold  regions  of  the  earth  proves  that  alcohol  renders  men 


HOW    TO    CARE    FOR    THE    CIRCULATORY    SYSTEM.        79 

less  able  to  withstand  the  cold.  Again,  some  think  that 
alcoholic  drinks  are  excellent  in  hot  weather.  Here, 
again,  they  are  mistaken.  Alcohol  does  cool  the  body, 
but  it  does  it  by  sending  blood  to  the  surface  and  increas- 
ing the  flow  of  perspiration  which  by  its  rapid  evapora- 
tion causes  a  sensation  of  coolness.  But  this  unnatural 
stimulus  to  the  glands  of  the  skin  tends  to  exhaust  and 
weaken  them. 

Frequent  stimulations  by  alcoholic  drinks  cause  permanent 
enlargement  of  the  capillaries.  The  red  face  of  the  drunk- 
ard is  caused  in  this  way.  The  heart  also  becomes  weakened 
by  frequent  excitements  and  is  liable  to  rapid  failure  at  about 
the  middle  age  of  life.  It  is  a  well-known  fact  that  habit- 
ual drinkers  nearly  always  die  when  attacked  by  such  epi- 
demics as  cholera,  smallpox,  etc.  It  is  because  the  circulatory 
system  is  not  equal  to  the  task  of  throwing  the  poison  of 
these  diseases  out  of  the  system. 

6.  Tobacco  and  the  Circulatory  Organs.  —  Doctors  fre- 
quently speak  of  a  "  tobacco  heart,"  or  a  "  smoker's 
heart."  What  do  they  mean  by  these  expressions  ? 
Tobacco  in  some  persons  especially  is  apt  to  cause  irregular 
action  of  the  heart,  sometimes  called  palpitation  of  the 
heart.  Such  fits  of  palpitation  are  not  only  very  disagree- 
able, but  there  is  actual  danger  of  complete  failure  of  the 
heart,  and  repeated  attacks  are  followed  by  derangements  of 
other  organs  from  want  of  proper  nourishment  by  the  great 
renewer  of  life  —  the  blood. 


80  PHYSIOLOGY    FOR   BEGINNERS. 

LESSON   26. 
Review  of  the  Circulatory  System. 

1.  Where    is  the  heart?     Describe  it  as  to  size  and 
shape.     Where  can  you  feel  it  beating  ? 

2.  How   many  cavities   in   the   heart  ?     Name   them. 
What  kind  of  blood  in  the  cavities  of  the  right  side  ?     In 
those  of  the  left  side  ?     Which  cavities  have  the  thickest 
walls  ? 

3.  Where  are  the  semilunar  valves  ?     What  do  they 
resemble  ?     Where  is  the  tricuspid  valve  ?     The  mitral 
valve  ?     What  kind  of  blood  flows  through  the  tricuspid 
valve  ? 

4.  What  is  the  pericardium  ?     What  lines  the  cavities 
of  the  heart  ? 

5.  How  many  times  does  the  heart  beat  in  a  minute  ? 
What  causes  the  sounds  of  the  heart  ? 

6.  Tell  all  you  can  about  the  aorta.      What  is  the 
main  trunk  of  the  arterial   system  ?      How  do  arteries 
differ  from  veins  ? 

7.  What  large  artery  may  be  felt   pulsating  in  the 
neck  ?     What  parts  does  it  supply  with  blood  ?      What 
main  artery  supplies  the  arm  ? 

8.  How  many  coats  have  the  arteries  ?     Which  is  the 
strongest  ?     Which  one  contains  muscular  fibers  ? 

9.  What  are  the  capillaries  ?     How  large  are  they  ? 

10.  How   much   blood   in   a   man   of    ordinary   size  ? 
What  is  the  color,  taste,  and  odor  of  blood  ? 

11.  What  change  takes  place  in  blood  after  it  leaves 
the  body  ?     What  is  fresh  blood  composed  of  ? 

12.  What  is  plasma  ?      What   substance  in   red  cor- 
puscles contains  iron  ? 


KEYIEW    OF    THE    CIRCULATORY    SYSTEM.  81 

13.  State  the  differences  in  the  composition  of  fresh 
and  coagulated  blood.     What  advantage  in  coagulation  ? 

14.  Of  what  use  are  the  red  corpuscles  ?    Trace  a  particle 
of  blood  from  the  right  to  the  left  side  of  the  heart,  nam- 
ing the  vessels  and  organs  it  must  pass  through.     In  the 
same  manner  trace  a  particle  from  the  left  to  the  right 
side. 

15.  Does  the  pulmonary  artery  contain  arterial  blood  ? 
What  is  the  portal  circulation  ? 

16.  What  makes  the  blood  circulate  ?     Explain  how 
the  physician  can  tell  about  the  beating  of  the  heart  by 
feeling  the  patient's  pulse  at  the  wrist. 

17.  How  long  does  it  take  for  any  particular  portion 
of  blood  to  complete  the  round  of  the  circulation  ? 

18.  What    are    lymphatics?      Describe    the    thoracic 
duct.     What   are    the    lacteals  ?     Where    are    the   lym- 
phatic glands  ?     Uses  of  the  lymphatics  ? 

19.  How  does  extreme  cold  and  heat  affect  the  circula- 
tory organs  ?     What  is  the  effect  of  exercise  on  circula- 
tion ?      Why  is   it   important  to  keep  the  feet  warm  ? 
Why  is  undue  excitement  injurious  ? 

20.  Where  would  you  tie  the  bandage  in  case  of  a 
wounded  artery  ?     How  would  you  know  it  was  an  artery 
and  not  a  vein  ? 

21.  How  does  alcohol  affect   the  circulation  ?      Does 
alcohol    make  one    really  warmer  ?      How  does   tobacco 
affect  the  heart  ? 

22.  The  pupil  must  bear  in  mind  that  the  heart,  arter- 
ies, capillaries,  and  veins  form  a  completely  closed  chamber, 
or  rather  a  cave,  or  house  with  many  chambers  and  pas- 
sages all  connected  together,  but  completely  closed  against 
the  outside  world.     To  make  this  clearer,  let  us  suppose 
ourselves  as  small  as  a  blood  corpuscle  and  placed  in  one 


82  PHYSIOLOGY    FOR   BEGINNERS. 

of  the  cavities  of  the  heart;  we  could  travel  through 
all  the  veins,  arteries,  and  capillaries  and  back  again  to 
the  heart,  without  finding  an  opening  large  enough  through 
which  to  escape.  Yet,  strange  to  say,  the  white  corpuscles 
have  been  known  to  escape  through  the  capillaries  and  get 
out  among  the  tissues.  They  do  this,  not  by  finding  or 
making  an  opening,  but  by  being  drawn  out  to  an  exceed- 
ingly small  thread  and  recovering  their  shape  again  on 
the  opposite  side.  This  is  truly  a  wonderful  phenomenon. 


LESSON  27. 
The  Machinery  of  Breathing. 

.  i.  Importance  of  Breathing.  — We  all  know  that  when 
an  animal  stops  breathing  it  dies  ;  that  is,  that  air  is  neces- 
sary to  life.  We  can  live  without  food  for  several  days, 
but  the  stoppage  of  respiration,  or  breathing,  for  a  few 
minutes  is  death.  All  animals  breathe,  that  is,  take  in 
the  oxygen  of  the  air  in  some  way.  In  the  lowest  forms 
the  little  oxygen  which  is  mixed  with  the  water  is  suffi- 
cient to  support  life,  and  in  some  it  simply  circulates 
through  the  animal  with  the  water  in  which  they  live. 
In  others  it  passes  through  them  in  a  set  of  tubes  which 
open  at  various  places  on  the  surface  of  their  bodies. 
All  higher  animals,  however,  have  a  larynx,  a  trachea, 
bronchial  tubes,  and  lungs.  These  are  the  organs  of 
respiration. 

2.  The  Larynx.  —  The  pharynx,  which  has  already 
been  described,  receives  air  from  either  the  passages  of 
the  nose  or  from  the  mouth.  From  the  pharynx  the  air 


THE  MACHINERY  OF  BREATHING. 


83 


passes  into  the  larynx,  which  is  a  short  tube,  or  box,  com- 
posed of  nine  pieces  of  cartilage  held  together  by  fibrous 
membrane.  You  can  feel  the  thy-roid  (shield-like)  carti- 
lage of  the  larynx  in  your  neck.  It  is  the  prominent, 
hard  lump,  sometimes  called  "  Adam's  Apple."  The  thy- 
roid cartilage  forms  the  greater  part  of  the  larynx.  The 
lower  and  narrowest  part  is  formed  by' the  cri-coid  (ring- 
like)  cartilage.  This  cartilaginous  box  has  a  peculiar  lid 
at  the  top  called  the  ep-i-glot-tis.  The  other  six  cartilages 
are  small  and  help  form  the  back  part  of  the  larynx. 


FIG.  17. 

The  epiglottis  is  somewhat  like  a  trap-door ;  it  stands  open 
to  admit  air,  except  when  food  or  drink  is  being  swal- 
lowed. Then  it  is  closed  to  prevent  the  food  from  enter- 
ing the  larynx.  Sometimes  when  we  attempt  to  talk  or 
breathe  while  swallowing,  a  little  food  or  drink  gets  into 
the  larynx  ("  goes  the  wrong  way,"  we  say),  and  violent 
coughing  is  caused. 

3.    The  Organ  of  Voice.  —  The  larynx  is  the  organ  of 
voice  as  well  as  a  part  of  the  breathing  machinery.     There 


84  PHYSIOLOGY    FOR   BEGINNERS. 

are  two  ligaments  covered  with  mucous  membrane  stretched 
across  the  sides  of  the  interior  of  the  larynx ;  these  are 
called  vocal  cords.  Various  degrees  of  tightening  of 
these  cords  cause  variations  in  the  sound  made  by  the  air 
being  forced  through  the  larynx  from  the  lungs.  The 
sound  is  modified  also  by  the  variations  in  the  size  of  the 
opening  between  'the  cords,  which  is  made  to  change  by 
muscles  in  the  walls  of  the  larynx. 

4.  The  Trachea.  —  The  trachea,  commonly  called  the 
wind-pipe,  extends  from  the  larynx  downward  about  four 
inches,  and  then  divides,  or  forks,  to  form  the  bronchial 
tubes.     It  is  a  peculiar  tube  made  up  of  incomplete  rings 
of  cartilage,  from  sixteen  to  twenty  in  number,  joined 
together  by  fibrous  membrane.     This  arrangement  secures 
the  proper  amount  of  flexibility,  and  is  at  the  same  time 
rigid  enough  to  remain  an  open  tube.     Its  diameter  is 
about  three-fourths  of  an  inch. 

5.  The  Bronchial  Tubes. — These  are  the  branches  of 
the  trachea.     The  picture  will  give  an  idea  of  the  form 
of  these  branches.     The  structure  is  very  similar  to  that 
of   the   trachea,  except   in   the   very  smallest   branches, 
where  the  cartilage  rings  are  wanting. 

6.  Mucous  Membrane.  —  A  continuous  layer  of  mucous 
membrane  lines  the  larynx,  trachea,  and  bronchial  tubes. 
That  in  the  trachea  and  bronchial  tubes  is  thickly  set 
with   cells   containing    fine,  hair-like   projections,  called 
cil-i-a.     They  have  the  peculiar  power  ojf  moving  or  wav- 
ing together,  like  a  field  of  grain  when  swayed  by  the 
wind.     This  motion  is  most  forcible  in  the  direction  of 
the  mouth,  so  that  small  particles  placed  on  them  are 
carried  upward.     In  this  way  dust  taken  in  with  the  air 


THE  MACHINERY  OF  BREATHING.  85 

is  in  part  expelled.  The  mucus,  secreted  by  the  mucous 
membrane,  serves  as  a  protection  from  the  irritating  in- 
fluence of  the  air. 

7.  The  Lungs.  — The  entire  cavity  of  the  chest,  except 
the  small  space  occupied  by  the  heart  and  its  blood  ves- 
sels and  the  esophagus,  is  filled  by  the  two  lungs.     The 
picture  gives  a  very  good  idea  of  their  shape  —  larger  at 
the  lower  part  and  tapering  upward  to  the  neck.     They 
are  a  light  pink  or  rose  color,  getting  darker  with  age. 
They  are  very  light  in  weight,  by  reason  of  the  air  they 
contain.     A  piece  of  lung  tissue  of  an  animal  that  has 
once  breathed  will  always  float  in  water. 

8.  Structure  of  the  Lungs. — Try  to  form  an  idea  of 
their  structure  by  imagining  a  hollow  tree  with  a  great 
number  of  branches,  each  branch  hollow  and  terminating 
in  a  little  bag  of  membrane.     The  trunk  of  the  tree  rep- 
resents the  trachea,  the  branches  the  bronchial  tubes,  and 
the  little  bags  of  membrane  at  the  tips  of  the  smallest 
branches  are  the  air  cells.     Now  imagine  twined  with  this 
tree,  another  somewhat  similar  in  shape,  but  containing 
a  red  fluid.     This  would  represent  the  pulmonary  artery 
and  its  branches.     Suppose  the  ends  of  the  branches  of 
this  last  tree  were  continuous  with  the  branches  of  sev- 
eral similar  trees.     These  would  represent  the  pulmonary 
veins.     The  smallest  branches  of  the  veins  and  arteries 
are  the  capillaries  of  the  lungs.     They  form  a  dense  net- 
work around  the  air  cells.     All  these  tubes  and  branches 
are  connected  by  a  fine,  fibrous  tissue,  and  lymphatic  ves- 
sels also  penetrate  every  part.     The  amount  of  surface  of 
the  interior  of  the  air  cells,  if  spread  out,  would  be  very 
great.     It  is  estimated  to  be  as  much  as  fifteen  hundred 
square  feet. 


86  PHYSIOLOGY    FOR    BEGINNERS. 

9.  The  Pleura.  —  The  cavity  of  the  chest  is  lined  with 
a  delicate,  serous  membrane,  which  turns  and  covers  the 
lungs,  and  thus  forms  a  complete  bag.  The  inner  sur- 
faces secrete  a  fluid  which  keeps  them  moist  and  prevents 
friction  when  the  lungs  move  in  the  chest.  This  mem- 
brane is  called  the  pleura.  When  it  is  inflamed,  the 
disease  is  known  as  pleurisy. 


LESSON  28. 
How  and  Why  we  Breathe. 

1.  Respiration. — This    is. only  another  name    for  the 
process  of  breathing.     It  consists  of  two  acts,  taking  in 
of  air,  which  is  called  inspiration,  and  .expelling  the  air, 
which  is  called  expiration.     Respiration  is  an  involuntary 
process.     We  can  hold  our  breath  for  a  time,  but  in  a  few 
seconds  an  exceedingly  uncomfortable  feeling  compels  us 
to  take  in  air.     When  an  animal  has  ceased  to  breathe  it 
is  dead,  or  will  be  in  a  very  short  time.     It  is  true  that 
there  are    some   cases  where  respiration   has  apparently 
stopped  and  the  person  appears  to  be  dead,  and  yet  after 
the  lapse  of  sometimes  many  hours  he  comes  to  life  again. 
In   these   cases  of   "  suspended  animation-,"  as  they  are 
called,  breathing  goes  on  to  a  very  slight  extent,  although 
unperceived. 

2.  How  the  Air  enters  the  Lungs. — The  air,  like  all 
other  matter,  has  weight.     The  entire  amount  of  atmos- 
phere  presses   upon    every   square   inch  of    surface,   by 
reason  of  its  weight,  with  a  force  of  about  fifteen  pounds. 
If  you  immerse  an  empty  bottle  in  water  the  water  will 


HOW   AND    WHY    WE    BREATHE.  87 

rush  in  until  it  is  filled.  All  objects  on  the  earth  are 
immersed  in  the  atmosphere.  The  moment  you  create 
a  cavity,  air  rushes  in  just  as  water  into  the  bottle.  You 
are  all  familiar  with  a  pair  of  bellows.  It  consists  of  two 
boards  lying  close  together,  with  their  edges  joined  by 
some  flexible  material,  as  leather.  When  you  pull  the 
boards  apart  you  create  a  cavity  between  them,  and  the 
air  rushes  in  at  the  hole  in  one  of  the  boards.  The  air 
enters  the  lungs  in  a  similar  manner.  The  cavity  of  the 
chest  is  enlarged  in  the  act  of  inspiration  in  two  ways : 
First,  by  the  descent  of  tire  diaphragm.  This  is  a  muscular 
partition  across  the  body,  dividing  the  cavity  of  the  chest 
from  the  cavity  of  the  abdomen.  When  at  rest  the 
diaphragm  is  convex  on  the  upper  side.  The  central 
portion  is  a  flat  tendon,  and  when  the  fibers  of  the  mus- 
cular part  contract  they  pull  the  center  down.  This 
increases  the  size  of  the  chest  cavity.  Second,  by  the 
elevation  of  the  ribs.  You  will  notice  in  the  picture  of  the 
skeleton  that  the  ribs  all  incline  downward  from  the  spi- 
nal column.  When  the  front  ends  of  the  ribs  are  raised 
they  stand  out  farther  from  the  spinal  column,  and  thus 
enlarge  the  cavity  of  the  chest.  The  muscles  between  the 
ribs  and  certain  others  of  the  back,  neck,  and  shoulders  all 
aid  in  raising  the  ribs. 

As  the  air  enters  the  lungs  all  the  little  air  cells  fill 
out,  and  the  lungs  are  increased  in  bulk  corresponding  to 
the  increased  size  of  the  chest  cavity. 

3.  How  the  Air  leaves  the  Lungs.  —  The  air  is  forced 
out  of  the  lungs  by  the  elastic  reaction  of  the  various 
tissues.  When  you  bend  a  stick  and  let  go,  it  springs 
back  with  great  force  of  elasticity.  Now,  when  the  dia- 
phragm is  drawn  down  by  its  muscular  fibers,  it  presses 


88  PHYSIOLOGY    FOB   BEGINNERS. 

the  organs  in  the  abdomen  against  the  elastic  walls  of  the 
latter,  which  spring  back  again  when  the  muscular  force 
is  relaxed.  The  ribs  are  returned  to  their  position  by  the 
elasticity  of  their  cartilages.  The  tissues  of  the  lungs 
which  have  been  stretched  by  the  inrushing  air  resume 
their  original  conditions  and  aid  in  drawing  out  the  air. 

4.  Rate  of  Breathing.  —  A  grown  person  breathes,  on 
an  average,   eighteen  times   per   minute.     Exercise  and 
other  circumstances  increase  this  rate.     Children  breathe 
more  rapidly  than  adults.     A  man  will  breathe  about  nine 
million  times  in  a  year. 

5.  Effect  of   Breathing  on  the  Air.  —  The  air  consists 
of  about  four  parts  nitrogen  gas,  one  part  oxygen  gas,  and 
about  four  one-hundredths  part  of  carbon  dioxide,  or  car- 
bonic acid  gas,  with  a  small  amount  of  vapor  of  water. 
When  it  comes  out  of  the  lungs  a  chemical  analysis  shows 
that  it  has  lost  something  and  gained  something.     It  has 
four  or  five  parts  less  of  oxygen,  and  about  four  parts 
more  carbon  dioxide.     It  has  also  an  increased  amount  of 
moisture  and  is  considerably  warmer  than  before.    The  red 
corpuscles  have  absorbed  some  of  the  oxygen  of  the  air 
and  carried  it  to  the  tissues,  there  to  be  given  up  for  use 
in  the  growth  and  repair  of  the  body.    The  carbon  dioxide 
is  a  result  of  the  destruction  of  the  tissues  which  is  con- 
stantly going  on  and  is  thrown  out  of  the  body  as  waste 
matter. 

6.  Voice.  —  The  sound  made   by  air  from  the   lungs 
driven  forcibly  through  the  larynx  is  called  voice.     These 
sounds    are    variously   modified,    separated,    and    joined 
together  in   the  mouth,  by  the  tongue,  teeth,  and  lips. 
This  joining  and  separating  of  sounds  is  called  articula- 


HOW  TO  CARE  FOR  THE  BREATHING  ORGANS.     89 

tion.  Many  animals  have  voice,  but  cannot  articulate 
sounds.  A  few,  as  the  parrot  and  raven,  have  been 
taught  to  articulate  quite  distinctly.  About  forty  distinct 
sounds  are  used  in  speaking  the  English  language.  Some 
animals,  as  insects,  make  their  characteristic  sounds  by 
the  rubbing  together  of  their  wings,  or  by  the  leg  against 
the  wing.  Such  sounds  are  difficult  to  distinguish  from 
vocal  sounds,  that  is,  sounds  made  through  the  larynx. 


LESSON  29. 
How  to  Care  for  the  Breathing  Organs. 

i.  The  Need  of  Pure  Air. — By  pure  air,  we  mean 
air  that  has  the  proper  proportion  of  oxygen,  nitrogen, 
and  watery  vapor,  and  contains  no  injurious  gases  or 
other  substances  that  would  injure  the  system.  The 
blood  needs  a  certain  amount  of  oxygen  at  all  times 
to  maintain  its  proper  condition  and  make  it  fit  to 
nourish  the  body.  If  the  air  be  mixed  with  other 
gases  the  amount  of  oxygen  will  be  to  that  extent 
lessened.  The  carbon  dioxide  given  off  in  respiration  is 
not  injurious  in  itself,  but  if  it  exists  in  an  unusual 
amount  it  displaces  too  much  of  the  oxygen.  But  the 
amount  seldom  reaches  an  injurious  degree.  The  greater 
danger  lies  in  substances  in  the  air  which  are  injurious  in 
themselves.  The  lungs  throw  off  a  certain  amount  of 
dead  matter  (organic  matter),  which,  if  inhaled  again,  is 
injurious.  A  poisonous  gas  is  often  given  off  from  cast- 
iron  stoves  when  not  properly  constructed.  Factories 
sometimes  produce  injurious  gases,  which  escape  into  the 
atmosphere.  Decaying  animal  bodies  and  vegetable  mat- 


90  PHYSIOLOGY   FOR   BEGINNERS. 

ter  produce  gases  which  are  injurious  when  inhaled.     It 
is  very  important  then  that  we  inhale  pure  air. 

2.  The  Need  of  Moisture  in  the  Air.  — All  air  contains 
some  water  in  the  form  of  an  invisible  vapor.     This  can 
be  shown  by  a  simple  experiment  which  you  should  try 
when  you  have  an  opportunity.     Fill  a  dry  glass  tumbler 
with  ice  cold  water  and  place  it  in  a  warm  room.     In  a 
few  minutes  the  outside  of  the  glass  will  be  quite  moist, 
the  water  even  collecting  in  drops  and  running  down  the 
sides  of  the  glass.     In  this  case  the  cold  glass  condenses 
the  moisture  of  the  air.     Too  much  moisture  in  the  air 
makes  breathing  difficult,  as  the  oxygen  is  diluted  and 
greater  effort  is  required  to  get  the  proper  amount.     The 
air  then  seems  heavy,  although  it  is  really  lighter,  as  the 
watery  vapor  is  lighter  than  the  air.     On  the  other  hand, 
very  dry  air   irritates  the  mucous  membrane  of  the  air 
passages.     A  vessel  of  water  placed  on  the  stove,  will,  by 
its  evaporation,  increase  the  moisture  of  the  air  in  a  room 
where  it  has  become  too  dry. 

3.  Dust  in  the  Air.  —  The  air  always  contains  more  or 
less  solid    matter  in  the  form  of  dust.     We  cannot  see 
this  dust  unless  it  is  illuminated  by  a  strong  light.     Some- 
times when  the  sun  shines  through  a  small  opening  in  the 
room,  we  see  bright  bands  of  dust  particles.     When  the 
dust  is  considerable  in  quantity,  it  irritates  the  lungs  and 
tends  to  produce  disease.     Floors  and  furniture  should  be 
kept  perfectly  clean,  and  rooms  should  be  frequently  opened 
to  keep  them  from  accumulating  dust. 

4.  Germs  of  Disease  in  the  Air.  —  The  microscope  has 
revealed  the  fact  that  the  air  may  contain  various  kinds 
of  germs  (seeds)  of  very  minute  plants,  and  it  is  believed 


HOW  TO  CARE  FOR  THE  BREATHING  ORGANS.     91 

that  nearly  all  diseases  are  caused  by  these  germs  getting 
into  the  blood  and  there  growing  and  multiplying.  This 
is  believed  to  be  true,  at  least,  of  the  contagious  diseases, 
as  smallpox,  diphtheria,  cholera,  etc.  Physicians  and  sur- 
geons now  take  great  pains  to  prevent  these  germs  from 
getting  into  the  blood  through  wounds,  and  to  rid  the 
air  of  them.  The  treatment  of  such  diseases  is  therefore 
more  successful  now  than  formerly.  The  air  in  the  im- 
mediate neighborhood  of  sick  persons  is  apt  to  contain 
germs  of  disease  which  will  affect  others.  Many  of  these 
germs  enter  the  blood  through  the  lungs.  Filth  and  dirt 
of  all  kinds  favor  the  growth  of  injurious  germs,  hence  clean- 
liness is  important.  Disinfectants  are  substances  which 
destroy  these  germs. 

5.  Ventilation. — That  we  may  not  breathe  the  same 
air  over  and  over,  there  should  be  a  constant  circulation 
of  air.     The  air  that  leaves  the  lungs,  as  we  have  learned, 
is  warmer,  and  rises  out  of  the  way  while  we  inhale  a  fresh 
amount ;  but  if  we  are  in  a  tight  room,  where  this  once- 
breathed  air  cannot  escape  and  a  proper  supply  of  fresh 
air  cannot  enter,  this  bad  air  mingles  with  the  pure  air, 
and  we  are  compelled  to  breathe  it  over  again.     A  room 
that  permits  the  ready  escape  of  foul  air  and  the  entrance 
of  fresh  air  is  said  to  be  ventilated. 

6.  "  Catching  Cold."  —  A  cold  is  a  peculiar  condition 
of  the  mucous  membrane,  usually  of  the  air  passages, 
caused  by  sudden   or   great  cooling  of  the  body.     This 
cooling  or  lowering  of  the  temperature  of  the   body  is 
usually  caused  by  draughts  of  cool  air.     Rooms  that  are 
improperly  ventilated  expose  persons  to  draughts  of  air 
which  may  cause  a  severe  cold  that  may  result  in  some 
serious  disease  of  the  respiratory  organs,  as  pneumonia, 


92  PHYSIOLOGY    FOR   BEGINNERS. 

bronchitis,  and  even  consumption.  There  is  very  little 
danger  of  taking  cold  in  a  draught  if  one  is  exercising, 
because  the  exercise  keeps  up  the  body  temperature ;  but 
when  sitting  still  in  a  strong  draught  the  danger  is  great. 
When  tired  and  heated  from  exercise  one  should  be  very 
careful  not  to  sit  still  where  there  is  a  strong  current  of  air. 

7.  Proper  Ventilation.  —  A  room  is  properly  ventilated 
when  the  fresh  air  has  free  access  and  the  foul  air  is  per- 
mitted to  pass  out,  in  such  a  way  that  no  one  is  exposed 
to  a  draught  of  cool  air.     In  a  room  with  a  fire  the  cold 
air  should  come  in  near  the  source  of  the  heat  and  be- 
come warmed  before  it  strikes  the  persons  in  the  room, 
and  the  warmed  air  should  be  permitted  to  escape  at  a 
point  farthest  from  the  source  of  the  heat. 

8.  Exercise  and  Respiration.  —  That  kind  of  exercise 
which  brings  into  use  the  muscles  of  the  arms  and  chest 
is  especially  beneficial  to  the  breathing  organs. 

Breathing  exercises  like  the  following  should  be  taken 
every  day :  Stand  erect,  throw  the  shoulders  back,  and 
slowly  inhale  ;  then  slowly  exhale.  Repeat  several  times 
in  succession.  Inhale  through  the  nose,  never  through  the 
mouth.  TJie  mouth  should  always  be  kept  closed  when  we 
are  not  eating,  talking,  or  singing.  The  nasal  passages 
warm  the  air,  and  catch  much  of  the  dust  that  would 
otherwise  enter  the  lungs. 

9.  Alcohol  and  the  Breathing  Organs.  —  Alcohol  causes 
an  increased  flow  of  blood  to  the  capillaries.     The  lungs 
are  thus  overfilled  and  the  exchange  of  gases  rendered 
imperfect.     Excessive  use   of   alcoholic  drinks  tends   to 
thicken  the  mucous  membrane  and  render  it  less  sensitive. 
The  drunkard  always  has  a  wheezy,  or  thick  and  unnat- 
ural voice. 


REVIEW    OF    THE    RESPIRATORY    SYSTEM.  93 

10.  Tobacco  frequently  irritates  the  mucous  membranes  of 
the  air  passages,  and  by  its  bad  effect  on  the  nervous  system 
injuriously  affects  all  the  organs  of  the  body,  and  among 
them  those  of  the  respiratory  system. 


LESSON  3O. 
Review  of  the  Respiratory  System. 

1.  What  gas  is  necessary  for  all  animal  life  ?     What 
are  the  organs  of  respiration  ? 

2.  Describe  the  larynx  in  your  own  language.     What 
happens  when  we  say  the  food  or  water  goes  the  wrong 
way  ?     What  is  Adam's  Apple  ? 

3.  Where  are  the  vocal  cords  ?     What  is  the  use  of  the 
epiglottis  ?     What  is  the  organ  of  voice  ? 

4.  What  is  the   use  of   the  trachea?     What  are   the 
uses  of  the  cartilage  rings  in  the  trachea  ?     What  are  the 
bronchial  tubes  ? 

5.  What  lines  the  larynx,  trachea,  and  bronchial  tubes  ? 
What  are  cilia  ?     What  is  the  use  of  them  ? 

6.  What  is  the  use  of  the  mucous  membrane?     Why 
are  the  lungs  so  light  in  weight  ? 

7.  What  and  where  are  the  air  cells  ?     What  are  they 
the  terminations  of  ?     What  surrounds  the  air  cells  ?     The 
capillaries  of  the  lungs,  which  are  the  terminations  of  the 
pulmonary  artery  and  the  beginnings  of  the  pulmonary 
veins.     Here  the  exchange  of  gases  is  made.     The  oxygen 
passes  through  the  walls  of  the  air  cells,  and  through  the 
capillary  walls,  and  into  the  red  corpuscles  of  the  blood, 
and  the  carbon  dioxide  passes  in  a  similar  manner  from 
the  blood  to  the  interior  of  the  air  cells. 


94  PHYSIOLOGY    FOR    BEGINNERS. 

8.  What  is  the  pleura  ?     What  other  membrane  that 
you  have  learned  about  is  it  similar  to  in  structure  and 
use? 

9.  What  is  the  difference  between  inspiration  and  ex- 
piration ?     What  is  the    difference  between  inspired  air 
and  expired  air  ? 

10.  What    makes    the    air   enter   the   lungs?      What 
drives  it  out  ?     How  fast  do  you  breathe  ? 

11.  What  is  the  difference  between  voice  and  articula- 
tion ?     Has  a  dog  voice  ?     Has  a  katy-did  voice  ?     No, 
its  music  is  instrumental,  not  vocal.     The  music  of  the 
canary  bird  is  vocal  music. 

12.  Do  we  need  pure  air  for  breathing  ?     Why  ?     Is 
very  dry  air  injurious  ?     Why  ?     What  is  the   effect  of 
dust  in  the  air  ?     What  are  disinfectants  ? 

13.  What   is  ventilation  ?     What  is  the   objection  to 
sitting  by  an  open  window  when  the  air  outside  is  cooler 
than   that   inside   of    the   room  ?     How  do   we    "  catch 
cold  "  ? 

14.  What  can  you  say  of   breathing   exercises  ?     Of 
alcohol  and  tobacco  in  connection  with   the   respiratory 
system  ? 


LESSON  31. 
The  Skin. 

i.  Definition.  — The  skin  is  the  layer  of  tissue  which, 
like  a  tight-fitting  but  elastic  garment,  covers  all  parts 
of  the  body  exposed  to  the  air,  except  those  parts  which 
are  covered  with  mucous  membrane.  It  is  a  garment 
easily  cleaned,  and  renews  itself  as  fast  as  it  wears  out. 


THE    SKIN. 


95 


It  consists  of  two  principal  layers,  the  epidermis,  cuticle 
or  scarf  skin,  and  the  derma  or  true  skin. 

2.  The  Epidermis.  —  This  is  the  outer  layer  of  the 
skin.  It  is  composed  of  what  is  called  horny  tissue  and 
has  no  blood  vessels  nor  nerves.  It  again  is  composed  of 
two  layers,  the  outer  one  of  hard,  flattened  cells  like 
scales.  These  are  continually  coming  off,  and  their  places 


fPIDEKN* 

««tt?(f 


FIG.  18. 

are  taken  by  new  ones  from  the  layer  beneath.  In  the 
scalp  these  scales  sometimes  accumulate  in  considerable 
quantity  and  are  known  as  "  dandruff.1'  The  deep  layer 
consists  of  rounded  cells  which  contain  a  coloring  matter 
called  the  pigment  of  the  skin.  In  those  people  called 
albinos  this  pigment  is  entirely  absent.  In  persons  of 
fair  complexion  there  is  very  little  pigment.  In  the 
negro  and  other  dark  races  it  is  very  abundant.  When 
it  is  found  thicker  in  spots  it  produces  "freckles." 


96  PHYSIOLOGY    FOR   BEGINNERS. 

3.  The  Derma,  or  True  Skin.  —  This  again  is  composed 
of  two  layers ;  the  outer  one  is  called  the  papillary  layer. 
It  consists  of  little  elevations  very  close  together.    In  the 
palm  of  the  hand  they  are  in  rows,  making  the  peculiar 
lines  we  see.     These  little  projections  contain  the  extrem- 
ities of  the  nerves  and  capillaries  of  the  skin.     The  next 
layer  is  called  the  corium.     It  is  tough  and  elastic,  and 
consists  of  bundles  of  fibers,  some  of  which  are  muscular 
fibers,  mingled  with  the  glands  of  the  skin,  fat,  and  the 
hair  follicles.     The  muscular  fibers  contract  when  exposed 
to  cold,  and  draw  the  skin  into  little  lumps.    This  appear- 
ance is  often  called  "  goose  flesh." 

4.  Uses  of  the  Skin.  —  The  skin  is  the  great  protector 
of  the  body.      The  epidermis,   being  without  nerves,  is 
insensible,  and  acts  as  a  protector  from  the  air  and  other 
objects.      It  also   prevents  the  too  rapid  escape  of  heat 
and  lessens  evaporation.     The  entire   skin  also  protects 
the  muscles  and  nerves  beneath,  and  prevents  evaporation 
and  loss  of  heat.     The  numerous  glands  in  the  skin  serve 
an   important   purpose   which   will   be   discussed  in  the 
following  lesson. 


LESSON  32. 
Hair,  Nails,  and  Glands  of  the  Skin. 

i .  The  Hair.  —  The  hair  is  really  composed  of  the 
same  kind  of  material  as  the  epidermis  of  the  skin.  The 
outer  portion  consists  of  scales  overlapping  like  shingles 
on  a  roof,  but  very  small  and  close  together,  so  that  it 
requires  a  high  power  of  the  microscope  to  show  it  so. 
Beneath  this  is  a  layer  of  long  cells  which  contain  a  pig- 


HAIK,    NAILS,    AND    GLANDS    OF    THE    SKIN.  97 

ment,  or  coloring  matter,  and  in  the  center  is  the  pith, 
consisting  of  cells  and  air  spaces. 

2.  How  Hair  grows. — A   hair  grows   from  the  root 
end.     When  you  pull  one  out  there  is  still  left,  in  a  little 
bag  called  the  hair  follicle,  a  little  germ  which  grows  to 
produce  a  new  hair.     This  hair  follicle  is  sometimes  in 
the  skin  and  sometimes  beneath  it.     When  hair  becomes 
gray  the   pigment  matter   disappears,  and  air  takes  the 
place  of  it  in  the  cells,  giving  the  white  appearance. 

3.  Uses  of  the  Hair.  —  The   hair   protects   the   parts 
which  it  covers  from  extremes  of  heat  and  cold.     It  also 
helps  to  lessen  the  force  of  blows  or  contact  with  objects, 
and  carries  off  the  sweat. 

4.  The   Nails.  —  The   nails,   like  the   hair,   are   com- 
posed of  the  same  material  as  the  epidermis  of  the  skin. 
A  nail  grows  from  the  root  and  under  surface,  the  body 
of  the  nail  being  pushed  out  as  the  new  growth  advances. 
The  free  end  and  upper  surface  of  the  nail  is  insensible, 
as  it  contains  no  nerves ;  but  the  tissue  at  the  root  and 
just  beneath  is  very  sensitive,  so  that  intense  pain  is  pro- 
duced  when  a  nail  is  crushed  or  pulled  out.     You  can 
readily  name  the  uses  of  the  nails.     Were  they  absent 
we  could  not  pick  up  small  objects,  and  the  ends  of  the 
fingers  and  toes  would  be  in  continual  danger  of  injury. 

5.  The  Sweat  Glands.  —  These  are  very  numerous  in 
all  parts  of  the  skin.     They  consist  of  very  fine  tubes, 
extending  from   the  surface  to    the  deepest  part  of   the 
skin  and  sometimes  beneath  it.     The  lower  end  is  coiled 
up  in  a  bunch,  and  the  opening  at  the  upper  end  is  called 
a  pore.     These  glands  secrete  the  perspiration,  or  sweat. 


98  PHYSIOLOGY    FOR   BEGINNERS. 

When  the  body  becomes  warm  in  a  heated  atmosphere, 
or  by  physical  exercise,  these  glands  pour  out  an 
abundant  supply  of  perspiration,  which  evaporates,  and 
this  evaporation  cools  the  body.  A  large  amount  of 
waste  material  is  also  thrown  off  in  this  way. 

6.  The  Oil  Glands.  —  These  are  found  to  some  extent 
in  the  skin  of  the  entire  body,  but  are  much  more 
numerous  on  the  scalp  and  face.  They  consist  of  clusters 
of  little  bags  in  the  deep  layer  of  the  skin  or  just  beneath 
it.  Each  gland  has  a  duct,  which  opens  either  on  the 
surface  or  by  the  side  of  the  root  of  a  hair.  They  secrete 
an  oil  which  serves  to  keep  the  skin  and  hair  soft  and 
protects  them  from  the  perspiration.  The  oil  is  carried 
by  capillary  attraction  along  the  entire  length  of  the 
longest  hair. 


LESSON  33. 
Mucous  and  Serous  Membrane. 

i.  Where  is  Mucous  Membrane?  —  In  this  book  we 
have  already,  in  several  places,  talked  about  mucous  and 
serous  membranes,  so  that  this  lesson  will  be  a  kind  of 
review.  The  mucous  membrane  is  really  one  continuous 
covering  or  lining,  although  it  has  very  many  parts.  It 
lines  or  covers  all  surfaces  that  are  exposed  to  the  air  and 
that  are  not  covered  with  skin.  It  lines  all  the  respiratory 
organs,  which  means  that  beginning  with  the  cavity  of  the 
nose,  it  extends  into  the  pharynx,  larynx,  trachea,  bron- 
chial tubes  large  and  small,  and  finally  into  the  air  cells 
of  the  lungs.  It  lines  the  alimentary  canal,  which  means, 
that  beginning  with  the  mouth,  it  lines  the  pharynx, 


MUCOUS    AND    SEROUS    MEMBRA&E*,    ;     ,....*.<}$. 

esophagus,  stomach,  small  and  large  intestines,  and  all  the 
ducts  of  glands  which  pour  their  secretion  into  this  ali- 
mentary canal,  as  the  ducts  of  the  salivary  glands,  the 
pancreas,  and  the  liver.  There  are  also  many  cavities  in 
the  bones  of  the  head  which  connect  with  the  cavities  of 
the  nose  and  pharynx,  and  they  are  also  lined  with 
mucous  membrane. 

2.  What  is  Mucous  Membrane?  —  It  consists  of  one  or 
more  layers  of  cells  of  different  shapes  and  sizes.    The  cells 
of  the  outer  layer  are  continually  coming  off  just  like  those 
of  the  epidermis.     The  shapes  of  the  cells  differ  in  differ- 
ent parts  of  the  body.     Figure  19  shows  the  form  of  the 
cells  of  the  mucous  membrane  of  the  trachea.     It  con- 
tains cilia,  which  were  described  in  a  former  lesson.     The 
outer  layer  has  no  blood  vessels,  and  with  some  exceptions 
no  nerves,  but  the  deeper  layer  is  abundantly  supplied 
with  both. 

3.  Uses  of   Mucous  Membrane. — It  serves  to  protect 
the  delicate  parts  which   it  covers.     It  secretes  a  fluid 
called  mucus.     This  keeps  its  surface  always  moist,  and 
protects  the  parts  from  the  air  and  from  dust  and  gases  in 
the  atmosphere.     In  the  alimentary  canal  it  prevents  its 
walls  from  adhering  together  and  aids  in  the  passage  of 
food  through  it. 

4.  Where  is  Serous  Membrane?  —  There  are  many  sur- 
faces in  the  body  which  are  not  exposed  to  air,  as  the  sur- 
face of  the  brain,  the  outside  of  the  stomach,  liver,  and 
other  organs  of  the  abdomen,  the  heart  and  lungs.     All 
such  surfaces  are  covered,  and  the  cavities  which  contain 
these  organs  are  lined  with  serous  membrane.     In   the 
chest  that   part  which   covers  the  lungs   and   lines   the 


lx)G  c    A     PHYSIOLOGY   FOR   BEGINNERS. 


walls  is  called  the  pleura,  and  that  which  covers  the  heart, 
the  pericardium.  In  the  abdominal  cavity  it  is  all  in  one 
continuous  piece,  and  is  called  the  per-i-to-ne-um.  A. 
continuous  serous  membrane  lines  the  heart  and  blood 
vessels.  That  covering  the  brain  and  spinal  cord  will  be 
mentioned  when  we  come  to  describe  those  parts. 

5.  What  is  Serous  Membrane?  —  It  resembles  mucous 
membrane  in  structure.  The  cells  are  usually  flattened, 
and  the  surface  is  always  smooth 
and  shining  and  kept  constantly 
moist  with  serous  fluid  secreted  by 
the  membrane. 


FIG.  19. 


6.   Uses  of   Serous   Membrane. — 

They  are  for  the  prevention  of  fric- 
tion when  one  part  moves  on 
another.  With  every  movement  of 
the  body  the  organs  are  shaken  and  slide  about  in  their 
cavities,  and  if  it  were  not  for  this  smooth,  moist  mem- 
brane, they  would  be  injured. 


LESSON  34. 
Secretion,  Excretion,  and  Absorption. 

i.  Definitions.  —  Here  are  three  words  which  we  must 
know  the  meaning  of,  as  used  in  Physiology.  The  living 
body  is  a  great  machine,  or  rather  a  great  laboratory  or 
workshop,  where  many  processes  of  manufacture  are  going 
on.  For  example,  the  food  is  digested,  and  for  this  pur- 
pose certain  fluids  are  necessary.  The  body  makes  these 
fluids  out  of  the  blood.  The  places  where  the  fluids  are 
made  are  in  the  glands.  The  process  of  making  these 


SECRETION,    EXCRETION,    AND    AB&dR£Tf Otf,;; J; 

fluids  in  the  glands  is  called  secretion.  Some  of  these 
fluids  serve  but  little  use  and  pass  more  rapidly  out  of  the 
system,  and  are  generally  called  excretions.  Thus  the 
saliva,  gastric  juice,  bile,  and  pancreatic  juice  are  usually 
called  secretions ;  for  they  are  produced  for  a  purpose,  that 
of  preparing  the  food.  But  the  perspiration,  containing  as 
it  does  injurious  elements  resulting  from  the  waste  of  the 
system,  and  being  of  use  only  to  cool  the  body  by  its 
evaporation,  is  usually  spoken  of  as  an  excretion. 

The  process  by  which  food  in  a  liquid  form  is  taken 
into  the  blood  through  the  capillary  walls  and  through 
the  lacteals  is  called  absorption.  The  word  is  applied 
also  to  the  accidental  taking  in  of  water  or  other  liquid 
substances  through  the  skin.  Also  we  call  that  absorption, 
where  one  part  of  the  body  which  is  no  longer  of  any  use 
is  carried  away  into  the  general  current  of  the  blood,  as 
the  gradual  removal  of  the  roots  of  the  temporary  teeth. 

2.  Perspiration.  —  A  certain  amount  of  water  is  con- 
stantly leaving  the  body  through  the  pores  of  the  skin. 
When  the  quantity  is  small,  it  evaporates  as  fast  as  it 
appears  on  the  surface  and  we  are  not  aware  of  the  loss, 
but  when  it  is  more  rapid  and  accumulates  as  moisture  on 
the  surface,  we  say  that  we  are  perspiring.  When  not 
sufficient  in  quantity  to  be  perceptible  to  the  eye,  we  call 
it  insensible  perspiration.  The  amount  of  insensible  per- 
spiration is  much  greater  at  some  times  than  others,  because 
when  the  air  is  dry  and  in  motion,  evaporation  is  much 
more  rapid.  The  evaporation  of  the  perspiration  cools 
the  body.  This  explains  how  our  feelings  or  sensations 
are  not  a  true  index  of  the  real  temperature  of  the  air ;  for 
when  the  air  is  dry  and  in  motion,  the  evaporation  is  more 
rapid  and  we  feel  cool ;  and,  on  the  other  hand,  although 


'--      i    APliySIOLOGY    FOR   BEGINNERS. 

the  temperature  may  be  the  same,  if  the  air  be  moist  and 
still,  we  feel  very  warm  because  the  heat  of  the  body  is 
not  carried  away  so  fast.  Strange  as  it  may  seem,  a  hot 
drink  will  cool  the  body,  because  it  increases  the  perspi- 
ration, which  by  its  evaporation  produces  a  sense  of  cool- 
ness. 

3.  The  Kidneys.  —  These   are   two  important   glands 
located  in  the  "  small  of  the  back  "  behind  the  intestines. 
Their  use  is  to  remove  from  the  body   certain  poisonous 
elements.     They   are   generally   spoken   of  as    excretory 
organs.     If  their  action  be  interrupted  for  any  length  of 
time,  the  person  dies  of  blood-poisoning. 

4.  Absorption.  —  We  have  already  spoken  of  absorp- 
tion of  the  food  from  the  alimentary  canal,  but  this  is  not 
the  only  place  where  absorption  may  take  place.     Certain 
poisons  are  so  powerful  that  if  a  drop  be  placed  on  the 
tongue  a  sufficient  quantity  is  absorbed  into  the  blood,  and, 
affecting  the  nervous  system,  produces  death  in  a  few  min- 
utes.    Some  poisons  are  readily  absorbed  if  merely  rubbed 
on  the  skin  anywhere  on  the  body.     If  the  epidermis  be 
removed,  absorption  is  very  rapid  from  the  surface. 

Doctors  sometimes  apply  "blisters,"  which  raise  the 
epidermis,  and  then  apply  medicines  to  the  raw  surface, 
that  it  may  be  readily  absorbed.  Tumors  and  unnatural 
growths  sometimes  disappear  of  themselves,  the  material 
being  absorbed  and  carried  out  of  the  body  as  waste  mat- 
ter. A  bath  sometimes  quenches  thirst,  because  a  suf- 
ficient amount  of  water  is  absorbed  through  the  skin. 

5.  Waste  and  Repair.  —  You  must  constantly  bear  in 
mind  that  no  part  of  the  body  is  in  a  state  of  perfect 
rest.     New  cells  are  forming  and  old  cells  are  disappear- 
ing.    The   material    for   the   new   cells   comes   from  the 


BATHING   AND    CLEANLINESS.  103 

blood,  and  the  blood  gets  it  from  the  food  that  is  digested. 
This  we  call  nutrition  or  repair  of  the  system.  The  ma- 
terial of  the  old  cells  is  thrown  into  the  blood  and  carried 
away  as  matter  that  is  no  longer  of  any  use.  This  is 
the  waste  of  the  system.  Life  seems  to  consist  physically 
in  this  constant  waste  and  repair  of  tissues.  The  body, 
then,  is  like  a  house  upon  which  workmen  are  continually 
employed,  removing  old  material  and  supplying  its  place 
with  new  material,  thus  keeping  the  house  ever  new. 


LESSON  35. 
Bathing  and  Cleanliness. 

1.  Need  of  Cleanliness.  —  We  learned  in  the  last  lesson 
how  foreign  substances  may  be  absorbed  from  the  surface 
and  poison  the  blood.     The  excretions  of  the  body,  if  again 
absorbed,  act  as  poisons.    Hence  they  should  not  be  permitted 
to  accumulate  on  the  surface.    Besides,  they  cause  dust  and 
dirt  to  adhere  to  the  surface  and  form  a  breeding-place 
for  the  germs  of  skin  diseases  of  various  kinds.     Cleanli- 
ness of  person  is  a  very  important  matter.     Many  diseases 
can  be  traced  directly  in  their  cause  to  want  of  personal 
cleanliness. 

2.  Value  of  Bathing.  —  The  entire  body  should  be  bathed 
with  water  at  least  once  every  week,  and  under  some  circum- 
stances every  two  or  three  days,  or  even   every   day.     In 
warm  weather  it  is  necessary  to  bathe  more  frequently. 
Occupations  which  expose  the  body  to  dust  and  dirt  make 
it  necessary  to  bathe  often.     Besides  the  need  of  bathing 
for  cleanliness,  it  is  frequently  important  to  take  a  bath 
for  curative  purposes.     A  severe  cold  may  often  be  cured  in 


104          PHYSIOLOGY  FOR  BEGINNERS. 

one  night  by  a  warm  bath,  but  care  must  be  taken  not  to  ex- 
pose the  body  to  cold  the  following  day  or  during  the  night, 
as  a  more  severe  cold  may  be  taken.  In  fevers  lukewarm 
or  cool  baths  are  valuable  to  lessen  the  unnatural  heat. 

3.  How  to  Bathe.  —  Where  it  is  possible,  a  bath-tub  in 
which  the  entire  body  may  be  immersed  is  a  great  con- 
venience and  luxury,  but  it  is  not  at  all  necessary  to  get 
the  full  benefit  of  a  bath.     A  gallon  of  water  in  any  ves- 
sel, a  sponge  or  soft  cloth,  and  a  towel  are  all  that  are 
essential.     A  thorough  drying  of  the  body  by  vigorous  rub- 
bing with  a  towel  is  important  in  cold  weather. 

4.  Kinds  of  Baths.  —  There  are  many  kinds,  as  warm, 
hot,  cold,  and  lukewarm  baths  ;  vapor  baths,  salt  water 
baths,  shower  baths,  Turkish  baths,  etc. ;  but  for  cleanli- 
ness the   simple  sponge  bath  as  described  in  section  3, 
with  water  of  a  temperature  agreeable   to   the    feeling 
is  as  good  as  any.     Cold   baths  are  not  advisable,  as  a 
shock  to  the  nervous  system  may  result,  which  often 
proves  injurious.     A   hot-water  bath  and  a  vapor  bath 
always  stimulate  at  first,  but  are  followed  by  depression ; 
and  one  should  have  a  good  rest  afterward.     Remaining 
too  long  in  the  bath  is  not  good,  nor  is  bathing  too  fre- 
quently.    Ten  or  fifteen  minutes  once  a  day  should  be 
the  limit. 

5.  Clothing.  — We  wear  clothes  to  keep  in  the  heat  of 
the  body  and  to  keep  out  excessive  external  heat.     The 
warmest  clothes  are  those  made  from  fur  or  feathers,  and 
next  to  these  are  woolen  and  silk  garments ;  next  comes 
cotton,   linen   being  the   coolest.      Wet  or  damp   clothes 
should  never  be  worn  for  a  minute,  if  possible  to  replace 
them  with  dry  ones.     If  compelled  to  wear  damp  clothes 


THE    BKAIN    AND    SPINAL    COKD.  105 

for  a  time,  one  should  exercise  to  keep  the  blood  circulat- 
ing. 

Clothing  that  is  worn  next  to  the  body  should  be 
changed  frequently,  and  if  not  washed  every  time  should 
be  well  aired.  It  is  better  to  have  one  garment  to  wear 
next  to  the  body  at  night,  and  another  in  the  daytime ; 
then  one  will  be  airing  while  the  other  is  in  use,  and  at 
the  end  of  a  week,  at  furthest,  both  should  be  washed. 
Bedclothes  should  be  aired  every  day  and  washed  fre- 
quently. 

6.  Care  of  the  Hair  and  Nails.  —  The  hair  should  be  fre- 
quently combed  and  brushed  to  keep  the  dirt  from  accumu- 
lating. Oil  should  not  be  put  on  the  hair,  unless  it  be 
unnaturally  dry  and  harsh.  The  finger-nails  should  receive 
careful  attention  every  day.  The  germs  of  disease  are  apt 
to  appear  in  the  dirt  which  accumulates  under  the  nails. 
They  should  be  carefully  cleaned  with  a  knife  and  nail- 
brush, with  a  little  soap  and  water.  Do  not  scrape  the 
upper  surface  of  nail  with  a  knife. 


LESSON  36. 
The  Brain  and  Spinal  Cord. 

1 .  The  Nervous  System.  —  We  now  come  to  study  an 
important  part  of  the  body.     It  is  that  part  that  controls 
and  governs  all  the  rest,  and  is  called  the  nervous  system. 
The  brain  and  spinal  cord  are   the  main  parts   of  the 
nervous  system,  and  form  the  subject  of  this  lesson. 

2.  What  is  the  Brain?  —  The  brain  is  a  large  mass  of 
nervous  matter  situated  in  the  cavity  of  the  head,  and  is 


106  PHYSIOLOGY  FOR  BEGINNERS. 

the  great  controlling  center  of  the  nervous  system.  It  is 
connected  with  the  spinal  cord  and  directly  or  indirectly 
with  all  the  nerves  of  the  body.  Its  average  weight  is 
a  little  more  than  three  pounds,  but  there  have  been 
cases  where  it  weighed  four  pounds.  As  a  general  rule, 
the  larger  the  brain,  the  greater  the  mental  power. 

3.  Coverings  of  the  Brain.  —  There  are  three  distinct 
coats  or  membranes  which  completely  surround  the  brain, 
inside  of  its  bony  case.     The  outer  membrane  is  called  the 
dura  mater,  from  the  Latin,  maaning  "hard  mother,"  the 
word  mother  being  used  in  the  sense  of  a  protector.     It  is 
a  firm  fibrous  membrane  and  serves  as  a  periosteum  to  the 
bone  as  well  as  a  protection  to  the  brain.     Next  to  the 
dura  mater  is  the  arachnoid  membrane  (spider-web-like). 
It  is  a  very  thin,  delicate    serous  membrane.     A  space 
between  the  arachnoid  and  dura  mater  contains  a  serous 
fluid.    There  is  also  a  space  between  the  arachnoid  and  the 
pia  mater  (soft  mother),  which  is  the  third  or  inner  mem- 
brane.     This   covering   consists  of   many  minute   blood 
vessels  united  by  fibers.    It  is  the  nourishing  membrane  of 
the  brain,  supplying  it  with  blood. 

4.  Parts  of  the  Brain.  —  The  brain   consists  of   four 
quite  distinct  parts  very  unequal  in  size.     Each  of  these 
again  is  double,  that  is,  they  are  partly  divided,  by  a 
fissure  extending  from  before  backward,  into  equal  por- 
tions.      These   parts    of    the   brain    will    be    separately 
described. 

5.  The  Cerebrum.  — This  is  the  largest  portion  of  the 
brain.     It  fills  all  the  space  in  the  cavity  of  the  head 
above  the  level  of  the  ears.     Looking  at  it  from  above,  we 
get  an  appearance  of  many  folds  and  furrows,  as  shown  in 


THE    BKAIN    AND    SPINAL    CORD. 


107 


B 


the  picture.  The  folds  are  called  convolutions.  They  are 
more  numerous  in  highly  intellectual  persons,  fewer  in  the 
most  intelligent  animals 
than  in  the  lowest  races 
of  men,  and  in  the  lowest 
quadrupeds  the  surface 
is  almost  smooth.  The 
furrows  which  separate 
the  convolutions  are 
about  an  inch  in  depth. 
The  object  of  the  con- 
volutions is  to  increase 
the  amount  of  surface, 
where  the  important 
nerve  cells  are  found. 
The  under  surface  of 
the  cerebrum  is  very  ir- 
regular, a  great  many  FlG-  20-  —UPPER  SURFACE  OF  CEREBRUM. 
portions  having  been  ^  Lo^^inal  fissure ;  B,  The  hemispheres. 

described  under  special  names  ;  but  little  is  known  of  their 
special  use. 

6.  The  Cerebellum.  —  This  is  the  next  largest  part  of 
the  brain.     It  is  sometimes  called  the  "  little  brain."     It 
lies  in  the  lower  and  back  part  of  the  cranial  cavity.     Its 
surface  is  marked  by  many  curved  furrows. 

7.  The  Pons  Varolii. — This  term  means  "the  bridge 
of  Yaroli,"  so  named  from  an  Italian  anatomist.    It  seems 
to  bridge  together  or  connect  the  other  parts  of  the  brain. 

8.  The  Medulla   Oblongata   (Oblong   Marrow).  —  This 
is  the  pyramid-shaped  portion  which  connects  the  rest  of. 
the  brain  with  the  spinal  cord.     It  is  the  lowest  portion 
of  the  brain,  lying  on  the  occipital  bone. 


108 


PHYSIOLOGY    FOR    BEGINNERS. 


9.  The  Interior  of  the  Brain.  —  The  brain  consists  of 
white  and  gray  matter.  These  will  vbe  described  in  the 
next  lesson.  If  the  cerebrum  be  cut  through  horizontally 
about  the  middle,  the  cut  surface  will  show  on  the  outer 
edge  a  layer  of  gray  matter  following  the  furrows,  and 
about  one-fourth  of  an  inch  in  depth.  Next  to  this  is  a 
mass  of  white  matter,  and  in  the  center  is  a  peculiar- 


FIG.  21. — THE  BASE  OF  THE  BRAIN. 

shaped  cavity,  one  in  each  hemisphere  or  half  of  the  cere- 
brum. These  cavities  are  called  ventricles.  Besides  these 
two  large  ones,  there  are  three  small  ones,  situated  deeper 
in  the  brain.  They  are  lined  with  a  serous  membrane 
and  contain  a  watery  fluid.  Cutting  through  the  cere- 
bellum, we  see  gray  matter  on  the  outside  and  white  on 
the  inside,  but  so  arranged  that  the  white  matter  appears 
as  a  tree  with  many  broad  branches.  This  appearance  is 
called  the  arbor  vitce  (tree  of  life).  The  pons  Varolii 


THE  NERVES.  109 

is  a  mixture  of  gray  and  white  matter,  and  the  upper 
part  of  the  medulla  oblongata  has  gray  matter  on  the 
outside  and  white  matter  on  the  inside ;  but  the  lower 
has  three  kinds  of  nerve  matter,  reversed  in  position. 

10.  The  Spinal  Cord.  —  This  is  a  long  cylinder  of  nerve 
matter,  that  extends  through  the  canal  formed  by  the  holes 
in  the  vertebras  of  the  spinal  column.  It  reaches  from 
the  medulla  oblongata  to  the  lower  edge  of  the  first  lum- 
bar vertebra,  or  about  the  distance  of  sixteen  inches.  It 
is  about  one-half  an  inch  in  thickness.  It  is  partly 
divided  by  fissures  into  two  equal  portions,  and  each  of 
these  again  into  two  columns.  The  gray  and  white 
matters  are  arranged  in  a  position  the  reverse  of  that  in 
the  brain ;  that  is,  the  gray  matter  in  the  center  and  the 
white  on  the  outside.  It  is  covered  by  a  continuation  of 
the  same  membranes  that  cover  the  brain.  At  each  ver- 
tebra a  pair  of  nerves  branch  off. 


LESSON    37. 
The  Nerves. 

i.  What  are  the  Nerves  ?  —  They  are  the  white  cord- 
like  branches  of  the  nervous  system  which  extend  to 
every  part  of  the  body,  dividing  and  subdividing,  some- 
what as  do  the  arteries  and  veins.  So  numerous  are  the 
small  branches  that  there  is  scarcely  a  point  on  the  sur- 
face of  the  body  where  you  will  not  wound  one  or  more 
by  pricking  with  the  finest  needle.  They  are  divided 
into  two  great  classes :  first,  those  branching  from  the 
brain  and  spinal  cord,  called  the  encephalo-spinal  nerves  ; 
and,  second,  those  which  form  networks  in  the  cavities  of 


110  PHYSIOLOGY   FOR   BEGINNERS. 

the  trunk  and  are  only  connected   with  the   others  by 
small  branches ;    these  are  called  sympathetic  nerves. 

2.  The  Cranial  Nerves.  —  Twelve  pairs  of  nerves  branch 
off  from  the  brain  and  are  called  cranial  nerves.  They 
are  numbered  in  the  order  they  leave  the  skull,  beginning 
at  the  front.  The  names  and  uses  are  as  follows  :  — 

1.  The  Olfactory,  or  nerve  of  smell. 

2.  The  Optic,  or  nerve  of  sight. 

3.  The   Motor  Oculi,  or  nerve  of  motion  to  the  eye- 
ball. 

4.  The  Pathetic,  also  a  nerve  of   motion  to  the  eye- 
ball. 

5.  The  Trifacial  has  a  branch  to  the  tongue,  being  a 
nerve  of  taste.     The  other  branches  go  to  the  eye  and 
different  parts  of  the  face,  and  are  nerves  of  motion  and 
sensation. 

6.  The  Abducens,  a  nerve  of  motion  to  eyeball. 

7.  The   Facial,  a  nerve  of  motion  to  the   muscles  of 
expression  in  the  face. 

8.  The  Auditory,  or  nerve  of  hearing. 

9.  The  Glosso-pharyngeal,  a  nerve  of  motion  and  sensa- 
tion to  the  pharynx.     It  has  a  branch  to  the  tongue,  which 
is  a  nerve  of  taste. 

10.  The  Pneumogastric,  a  nerve  of  motion  and  sensa- 
tion to  the  lungs,  stomach,  and  heart. 

11.  The  Spinal  Accessory,  a  nerve  of  motion  and  sensa- 
tion to  muscles  of  neck. 

12.  Hypoglossal,  a  nerve  of  motion  to  the  tongue. 

3.  The  Spinal  Nerves.  —  From  the  spinal  cord  are  given 
off  thirty-one  pairs  of  nerves  known  as  spinal  nerves. 
They  pass  out  of  the  spinal  canal  from  openings  between 


THE    NERVES. 


Ill 


the  vertebrae,  and  are  distributed  to  the  trunk  and  limbs. 
They  are  all  nerves  of  motion  and  general  sensation. 

4.  Ganglia.  —  These  are  knots  or  little  masses  of  gray 
and  white   matter  in  the  course  of   the  nerves.     Thus, 
each  spinal  nerve  has  two  roots,  and  on  one  of  them  is  a 
ganglion.     There  are  also  ganglia  on  some  of  the  cranial 
nerves. 

5.  The  Sympathetic  Nerves.  —  These  are  so  called  be- 
cause they  closely  connect  the  various  organs  of  the  body 


FIG.  22. — VARIOUS  FORMS  OF  NERVE  CELLS. 

and  are  supposed  to  produce  a  sympathy  of  one  organ 
for  another,  that  is,  if  one  organ  is  injured  or  diseased, 
other  organs  may  be  deranged  also.  The  sympathetic 
system  of  nerves  consists  of  two  chains  of  ganglia,  con- 
nected by  nerves  to  each  other  and  to  the  cranial  and 
spinal  nerves,  and  sending  branches  to  the  organs  of  the 
thorax  and  abdomen.  These  ganglia  lie  in  front  of  the 
spinal  column. 

6.    Structure    of    Nervous    Matter.  —  All   nerves   and 
nervous  matter  consist  of  either  white  or  gray  matter  or 


112  PHYSIOLOGY  FOR  BEGINNERS. 

both.  The  gray  matter  is  found  in  the  central  part  of 
the  brain,  in  certain  large  masses  or  ganglia  at  the  base 
of  the  brain,  in  the  center  of  the  spinal  cord,  and  in  the 
ganglia.  It  is  of  a  grayish  or  ashy  color,  tinged  with 
red.  It  is  soft  and  pulpy,  easily  broken  down  by  pressure 
of  the  finger.  It  consists  of  a  collection  of  cells  em- 
bedded in  a  fine  network  of  fibers.  The  white  matter  is 
found  in  the  center  of  the  brain,  the  outside  of  the  spinal 
cord,  and  composes  the  entire  substance  of  the  nerves.  It 
is,  with  some  exceptions,  of  a  dull  white  color.  It  consists 
of  numerous  small  fibers  united  by  a  network  of  fibrous 
tissue  similar  to  that  in  the  gray  matter. 


LESSON  38. 
How  the  Body  is  Governed. 

i.  The  Use  of  the  Nervous  System  in  General.  —  Like 
a  well  regulated  factory  or  business  house,  the  various 
organs  and  parts  of  the  body  are  governed  or  managed 
according  to  a  plan.  Every  part  has  its  special  work  to 
do,  and  they  all  work  in  harmony  when  in  a  state  of 
health.  Thus,  saliva  is  secreted  in  the  mouth,  and  bile  in 
the  liver,  when  the  need  for  them  exists  in  the  stomach 
and  intestines.  Strike  at  the  eye,  and  the  lid  is  quickly 
drawn  down  to  protect  it.  Touch  the  foot  with  a  hot 
iron,  and  quickly  the  muscles  of  the  leg  contract  and 
draw  it  away  from  danger.  The  general  function  or  use 
of  the  nervous  system  is  controlling  and  governing  the 
body.  This  is  brought  about  in  three  ways :  First,  a 
peculiar  activity  we  call  nerve  force  seems  to  originate  in 
the  cells  of  the  gray  matter.  If  these  cells  be  destroyed, 


HOW  THE  BODY  IS  GOVERNED.          113 

all  nervous  activity  at  once  ceases.  Second,  a  power  of 
transmitting  or  carrying  this  nerve  force  to  and  from  the 
cells  of  the  gray  matter.  This  power  lies  in  the  nerve 
fibers  of  the  white  matter.  Sever  these  fibers,  and  the 
part  to  which  they  are  distributed  has  no  longer  power  to 
act.  Third,  a  power  of  receiving  impressions  from  the 
world  outside  of  the  body.  Thus,  the  retina  of  the  eye 
receives  impressions  which  inform  us  of  the  color,  shape, 
and  size  of  objects  without  touching  them.  The  termina- 
tion of  the  auditory  nerve  receives  impressions  we  call 
sounds ;  and  so  on.  Different  nerve  endings  receive  dif- 
ferent .kinds  of  impressions. 

2.  The  Special  Use  of  the  Cerebrum.  —  The  cerebrum 
is  the  organ  of  mind.     It  is  that  part  which  thinks  and 
knows  and  wills  or  determines.     You  decide  that  you  will 
stand  up,  or  run,  or  sit  down,  or  write,  or  work,  or  play. 
You  could  not  do  any  of  these  without  the  cerebrum  and 
be  conscious  of  doing  them.     You  might  walk  or  write 
in  your  sleep,  but  you  would  have  no  knowledge  of  this 
action.     The  cerebrum  is  that  which  knowingly  produces 
action.     Animals  will  leap  and  walk   and  perform  vari- 
ous actions  when  the  cerebrum  has  been  removed,  but  these 
are  not  conscious  movements  and  are  always  produced  by 
a  stimulus  of  some   kind,  as  when  you  jerk  your  hand 
away  from  a  hot  stove  before  you  are  conscious  of  its 
existence.     This  unconscious  action  is  often  called  reflex 
action.     Reflex  action  may  be  said  to  be  motion  without 
the  use  of  the  cerebrum. 

3.  The  Special  Use  of  the  Cerebellum.  —  The  cerebel- 
lum seems  to  be  for  the  special  purpose   of  controlling 
the  muscular  movements.     A  pigeon  with  its  cerebellum 
removed  seems  to  know  what  is  going  on  around  it  and 


114  PHYSIOLOGY    FOR   BEGINNERS. 

what  it  wants  to  do,  but  is  unsteady  in  its  gait  and  misses 
the  food  it  pecks  at.  It  acts  somewhat  like  a  man  who 
is  slightly  intoxicated.  The  man  tries  to  walk  straight, 
but  cannot,  for  he  has  lost  perfect  control  of  his  muscles. 

4.  The  Nerve  Centers.  —  Most  of   the  regular   actions 
of  the  body,  as  breathing,  beating  of  the   heart,  etc.,  are 
controlled  by  special  nerve  cells  located  in  the  medulla 
oblongata.     Thus,  in  a   frog,  the   brain   may  be  all  re- 
moved except  the  medulla,  and  the  spinal  cord  completely 
destroyed,  and  yet  the  animal  breathes  and  its  blood  con- 
tinues to  circulate.     But  if  a  certain  point  in  the  medulla 
be  destroyed,  breathing  and  the  beating  of  the  heart  im- 
mediately stop.     The  medulla  oblongata  may  be  said  to 
be  the  great  center  of  the  nervous  system,  so  far  as  mere 
animal  life  is  concerned.     The  quickest  way  to  produce 
death  in  an  animal  is  to  paralyze  the  medulla.     Hanging 
does  this  quickly  by  causing  the  axis  vertebra  to  press 
suddenly  upon  the  spinal  cord  at  the  point  where  it  joins 
the  medulla.     All  gray  nerve  matter  acts  as  nerve  centers 
where  nerve  force  originates,  but  the  great  centers  which 
control  the  most  important  work  of  the  body  are  in  the 
medulla  oblongata. 

5.  Special  Use  of  the  Spinal  Cord.  —  The  white  matter 
of  the  spinal  cord  conducts  nervous  impressions  from  the 
various  parts  of  the  body  to  the  brain,  and  from  the  brain 
to  the  various  parts  of  the  body.     Thus,  if  your  great  toe 
strikes  a  stone,  an  impulse  passes  along  a  nerve  until  it 
reaches  the  spinal  cord,  and  from  there  it  is  conveyed  to 
the  cerebrum,  and  you  are  conscious  of  the  pain  produced. 
Yet  all  impressions  do  not  reach  the  cerebrum.    For  if  you 
touch  the  toes  of  a  frog  after  its  head  has  been  cut  off,  it 
will  move  as  if  trying  to  get  away,  perhaps  even  make 


HOW  THE  BODY  IS  GOVERNED.          115 

quite  a  leap ;  also,  if  you  tickle  the  foot  of  a  sleeping  boy, 
he  will  move  the  leg,  even  though  unconscious  In  such 
cases  we  conclude  that  the  gray  matter  of  the  spinal  cord 
originates  impressions  which  are  sent  out  on  the  nerves, 
and  causes  the  muscles  to  contract ;  and  this  we  call  re- 
flex action.  Another  use  of  the  spinal  cord,  then,  is  to 
act  as  a  kind  of  secondary  brain,  impressions  passing  no 
further  than  the  central  gray  matter  of  the  cord,  thus 
relieving  the  brain  of  part  of  its  work. 

6.  Advantages  of  Reflex  Action. — By  having  nerve 
centers  besides  those  in  the  brain,  the  latter  is  relieved  of 
part  of  its  work,  just  as  the  head  manager  of  a  large 
business  house  need  not  give  attention  to  many  of  the 
details  of  the  business,  but  can  have  trusted  overseers  to 
look  after  the  minor  matters.  When  we  have  once 
learned  to  do  any  kind  of  mechanical  work,  we  do  it  with 
very  little  thought.  You  do  not  have  to  think  how  you 
shall  walk  on  a  smooth  road.  You  can  even  walk  and  be 
for  a  time  unconscious  that  you  are  walking.  So  you  can 
become  so  accustomed  to  writing  that  your  pen  will  form 
the  letters  without  thought  on  your  part.  In  such  cases 
the  brain  occupies  itself  with  more  important  matters, 
and  this  kind  of  work  is  carried  on  by  centers  in  the 
spinal  cord.  There  is  also  a  higher  kind  of  reflex  action, 
which  may  be  called  automatic  ("  self-action  ").  Thus  we 
breathe  and  the  heart  beats,  the  glands  secrete  and  the 
food  is  digested,  all  independent  of  the  actions  of  our 
minds.  It  is  very  fortunate  that  such  is  the  case,  for 
if  we  were  obliged  to  think  and  give  attention  to  these 
matters,  we  might  permit  other  matters  to  take  their 
place  in  our  minds,  and  we  might  forget  to  breathe  or 
keep  the  blood  circulating,  and  die  from  our  own  careless- 


116  PHYSIOLOGY    FOR    BEGINNERS. 

ness.     The  centers  for  such  automatic  action  are  in  the 
medulla  oblongata. 


LESSON  39. 
Care  of  the  Nervous  System. 

1.  Health  of  Other  Organs.  —  When  one  part  of  the 
body  suffers,  other  parts  suffer  more  or  less.     The  nervous 
system  cannot  be  in  good  condition  without  good  blood, 
which  nourishes  it.     There  can  be  no  good  blood  without 
proper  digestion,  circulation,  and  excretion.     There  must 
be  a  proper  change  of  gases,  —  the  reception  of  oxygen  and 
throwing  out  of  carbon  dioxide;  and  this  depends  upon 
proper  working    of    the   respiratory   organs.     Therefore 
to  have  a  sound  mind   one  must  have  a   healthy  brain 
and  nervous  system,  and  to  have  a  healthy  nervous  system 
one  must  give  attention  to  the  rules  of  health  pertaining  to 
all  the  other  systems. 

2.  Mental  Excitements.  — The  mind  and  body  mutually 
act  upon  each  other.     Any  disturbance   of   the   nervous 
system  affects  the  mind,  and  any  powerful  excitements  of 
the  mind  affect  the  nervous  system.     Powerful  "spells" 
of  anger,  excessive  fear  and  grief,  and  even  great  joy  dis- 
turb the  nervous  system,  and  through  it  the  processes  of 
digestion,    secretion,    respiration,  and    circulation.     The 
nourishment   of  the  nerve  matter  is  thus  lessened   and 
the  nerve  tissue  is  injured. 

3.  Mental  Work. — The  nervous  system  is  capable  of 
accomplishing  an  enormous  amount    of  work  when   the 
work  is  of  a  proper  kind.     Mere  study  and  mental  occu- 
pation are  not  injurious,  unless  very  excessive.     The  mind 


CARE    OF    THE    NERVOUS    SYSTEM.  117 

is  always  active  during  waking  hours,  even  when  we 
make  no  effort  to  employ  it.  You  are  always  thinking 
about  something,  whether  it  be  of  importance  or  not;  the 
heart  continues  to  beat,  the  blood  to  circulate,  breathing 
goes  on;  and  all  of  these  involve  nerve  activity.  Even 
in  sleep  the  mind  acts  partially.  Dreaming  is  partial 
action  of  the  mind.  It  is  not  simply  work,  then,  which 
injures,  but  misdirected  and  unnatural  work.  All  worry, 
excitement,  and  emotion  are  unnatural,  and  when  long 
continued  rapidly  exhaust  the  nerve  force.  One  needs  a 
change  of  mental  work,  so  that  while  one  set  of  nerve 
cells  are  occupied  another  may  be  resting.  In  this  respect 
the  nerves  are  like  the  muscles. 

4.  Sleep.  —  During  sleep  all  the  powers  of  the  body  are 
renewed.  A  proper  amount  of  sleep  is  of  the  greatest  impor- 
tance, especially  to  the  health  of  the  nervous.  Children  and 
old  people  require  more  sleep  than  others.  Business  and 
social  matters  frequently  keep  persons  awake  when  they 
permit  their  minds  to  dwell  upon  them.  We  cannot  con- 
trol our  thoughts  except  in  one  way,  that  is,  we  can  avoid 
thinking  of  one  thing  by  thinking  of  another.  So,  the 
best  way  to  get  to  sleep  is  to  think  of  as  many  different 
things  as  possible,  —  as  it  were,  encourage  the  mind  to 
wander  from  one  thing  to  another.  When  it  is  concen- 
trated on  one  thing,  sleep  will  not  come.  You  can  also 
avoid  evil  thoughts  by  trying  to  think  of  something  that  is 
not  evil.  One  should  never  take  medicine  for  the  purpose 
of  causing  sleep,  without  the  advice  of  a  physician.  The 
proper  time  for  sleep  is  during  the  hours  of  darkness. 
Go  to  bed  early  enough  to  get  all  the  sleep  you  need  before 
daylight  in  the  morning. 


118  PHYSIOLOGY    FOR    BEGINNERS. 

5.  The  Effects  of  Alcohol  on  the  Nervous  System.  — 
Alcohol  acts  on  all  the  organs  of  the  body  by  first  derang- 
ing the  nervous  system.     This  disturbance  of  the  nervous 
system  naturally  weakens  and  impairs  it,  and  as  a  result  a 
great  many  nervous  diseases  are  liable  to  occur.     Dr.  Beard 
says:  "There,  is  scarcely  a  nervous  disease  known  to  science 
that  excess  in  the  use  of  alcoholic  liquors  may  not  bring  on  or 
aggravate.     General  debility)  neuralgia,  insomnia  (sleepless- 
ness]^ epilepsy  ('fits '),  paralysis  of  every  form  and  type,  insan- 
ity in  all  its  grades,  as  well  as  delirium  tremens,  may  find  in 
alcohol  their  exciting  and  predisposing  causes."    Worst  of  all 
is  the  effect  on  the  mind.     The  moral  powers  become  degen- 
erated, and  the  man  cannot  control  his  appetite  when  the  habit 
has  been  continued  for  a  long  time,  and  lie  becomes  a  con- 
firmed drunkard. 

6.  The  Effects  of  Tobacco  on  the  Nervous  System.  —  All 
young  people  are  injuriously  affected  by  the  use  of  tobacco. 
It  produces  a  tendency  to  nervous  diseases  of  various  kinds. 

7.  Tea,  Coffee,  and  Chocolate.  —  These  drinks  are  not 
generally  injurious  to  persons  after  thirty  years  of  age, 
if  used  in  moderation,  but  their  effects  on  the  young  are  fre- 
quently as  bad  as    that  of  tobacco   and   alcoholic   drinks. 
Milk  and  water  are  the  proper  drinks  for  children  and  young 
people. 


LESSON  4O. 
Review  of  the  Nervous  System. 

1.  The  nervous  system  is  that  part  of  the  body  which 
governs  and  controls  all  of  the  other  parts. 

2.  The  brain  and  spinal  cord  are  the  principal  central 
organs  or  headquarters  of  the  nerve  force,  as  they  con- 


REVIEW   OF   THE    NERVOUS    SYSTEM.  119 

tain  the  gray  matter,  or  that  in  which  nerve  power  origi- 
nates. 

3.  The  nerves  proper  are  the  collections  of  fibers  which 
distribute  the  nerve  force  from  the  nerve  centers  in  the 
brain  and  spinal  cord. 

4.  The  brain  and  spinal  cord  are  well   protected   by 
three  peculiar  membranes,  the  inner  one  of  which  also 
furnishes  nourishment  to  their  substance.     What  are  the 
names  of  these  membranes  ? 

5.  The  brain  consists  of  four  principal  divisions.    Which 
is  the  largest  ?     Which  part  connects  the  brain  with  the 
spinal  cord  ? 

6.  Name  all  the  places  where  gray  nerve  matter  is 
found.     How  is  the  amount  of  gray  matter  increased  in 
the  brain  and  yet  exists  on  the  surface  ? 

7.  The  interior  of  the  brain  has  certain  cavities  contain- 
ing fluid.     The  use  of  these  cavities  is,  doubtless,  to  lessen 
the  danger  of  shocks  when  the  head  strikes  any  object 
forcibly.     What  do  we  call  these  cavities  ?     How  many 
are  there  ? 

8.  How  does  the  arrangement  of  gray  and  white  mat- 
ter in  the  spinal  cord  differ  from  that  in  the  brain  ? 

9.  All  nerve  fibers  convey  either  power  of  motion,  gen- 
eral sensation  (as  pain),  or  some  special  sensation  (as  sight, 
hearing,  etc.).     The  first  are  called  motor  fibers  and  the 
last  two  are  called  sensory  fibers.     The  spinal  nerves  all 
have  both  motor  and  sensory  fibers.     The  cranial  nerves 
are  of  three  kinds ;  some  contain  all  motor  fibers,  some  all 
sensory  fibers,  and  others  contain  both  motor  and  sensory 
fibers.     The  eye,  not  even  by  the  aid  of  the  microscope, 
can  tell  any  difference  between  motor  and  sensory  fibers. 
We  only  know  that  if  certain  fibers  be  cut  the  power  of 
motion  is  lost  in  that  part  to  which  the  nerve  goes,  and 


120  PHYSIOLOGY  FOR  BEGINNERS. 

if  certain  others  be  cut  the  power  of  sensation  is  lost  in 
the  part. 

10.  Although  the  brain  is  the  great  center  of  the  ner- 
vous system,  yet  we  suffer  no  pain  if  a  portion  of  it  be  cut 
or  bruised.     There  could  be  no  pain  without  a  brain,  yet 
the  brain  itself  suffers  no  pain.     This  is  a  curious  fact. 

11.  "  Heart-burn"  is  a  peculiar  pain  in  the  region  of 
the  heart.     It  is  caused  by  some  irritation  in  the  stomach. 
Sometimes  the  heart  takes  spells  of  "  palpitating,"  that 
is,  beating  rapidly  and   irregularly.     In  such   cases  the 
heart  itself  is  not  impaired,  but  the  cause  may  be  sought 
in  the  digestive  system.     This  unnatural  action  of  one 
organ,  caused  by  an  irritation  in  another,  is  brought  about 
through    the   nerves   of   the    sympathetic   system,  which 
connects  all  the  organs  of  the  interior  of  the  trunk.     A 
severe  blow  on  the  abdomen,  although  it  does  not  break 
the  skin  or  rupture  any  of  the  tissues,  may  cause  sudden 
death  by  the  severe  shock  to  the  nerves  of  the  sympathetic 
system. 

12.  Comparing  the  nervous  system  to  a  business  house 
or  great  factory,  what  part  would  you  say  resembled  the 
manager  or  head  of  the  firm  ?     Comparing  the  nervous 
system  to  a  telegraphic  apparatus,  we  can  say  the  nerve 
cells  of  the  gray  matter  are  like  the  batteries  which  pro- 
duce the  electricity,  and  the  fibers  of  the  white  matter  are 
like  the  wires  which  convey  the  electricity. 

13.  What  part  of  the  nervous  system  is  the  seat  of 
thought  and  consciousness?     Could  an  animal  with  its 
head  cut  off  suffer  pain?     What  makes  a  chicken  jump 
about  after  its  head  is  cut  off  ? 

14.  Explain  how  the    mind  and  body  act  upon  each 
other.     Can  there  be  a  sound  mind  without  a  sound  body  ? 
While  it  is  true  that   some  great  mental  achievements 


THE    EYE.  121 

have  been  made  by  men  when  they  were  suffering  severely 
from  disease,  yet  such  mental  efforts  could  not  last  long. 
The  relations  of  mind  and  body  are  very  close  ones. 


LESSON  41. 
The  Eye. 

1.  How  the  Eye  is  Protected. — You  know  what  the 
eye  is  and  what  it  is  for,  but  perhaps  you  have  never 
thought  what  a  wonderful  instrument  it  is  and  how  well 
it  is  protected  from  injury.     First,  it  is  well  surrounded  by 
strong  bony  walls,  called  the  orbits.     Ordinary  blows  are 
received  by  the  firm  rim  of  bone  in  front,  and  nothing  but 
a  well-aimed  thrust  of  a  sharp  instrument  can  affect  the 
eye.     Again,  the  orbit  is  much  larger  than  the  eye,  and 
the  extra  space  is  filled  with  a  cushion  of  fat,  which  lessens 
any  shocks  which  would  occur  from  falls  or  blows  on  the 
head. 

The  eyebrows  shield  the  eye  from  excessive  light  and 
direct  the  perspiration  aside.  The  eyelids,  composed  of 
cartilage  and  skin,  act  both  voluntarily  and  involuntarily, 
closing  instantly  as  danger  approaches.  Their  edges  con- 
tain glands  which  secrete  an  oily  fluid  which  prevents 
the  tears  from  overflowing  on  the  face.  The  tears  keep 
the  surface  of  the  eye  moist  and  clear.  The  eyelashes 
shade  the  eye  and  act  as  feelers  to  warn  of  danger. 

2.  Where  the  Tears  come  from.  —  In  the  upper  and 
outer  corner  of  the  orbit  is  a  gland  called  the  lachrymal 
gland.     It  secretes  the  fluid  called  tears.     The  tears  are 
constantly  pouring  out  through  several  little  ducts  upon 


122 


PHYSIOLOGY    FOR    BEGINNERS. 


the  surface  of  the  eye.  The  frequent  winking  of  the 
eyelids  causes  the  fluid  to  spread  over  the  eyeball.  At 
the  inner  corner  of  the  eye  are  two  little  openings,  which 
receive  the  fluid  and  conduct  it  to  the  lachrymal  sac,  from 
which  it  passes  into  the  nasal  duct  and  through  it  into 
the  cavity  of  the  nose.  Here  it  evaporates,  usually  as 
fast  as  discharged.  When  we  weep,  the  amount  of  the 
tears  is  excessive  and  they  flow  over  on  the  face.  The 
surface  of  the  eye  and  the  inside  of  the  eyelids  are 


FIG.  23.  —  MUSCLES  OF  THE  EYE. 


covered  with  a  thin,  delicate  mucous  membrane  called 
the  con-junc-ti-va.  It  is  very  sensitive  and  serves  to 
protect  the  eye. 

3.  Size  and  Shape  of  the  Eyeball.  —  It  is  about  an  inch 
in  diameter  from  side  to  side  and  from  above  downward, 
but  the  diameter  from  before  backward  is  a  little  greater. 
It  is  like  a  sphere  with  a  part  of  a  smaller  sphere  placed 


THE    EYE. 


123 


upon  it.     Six  little  muscles  attached  to  the  eyeball  serve 
to  turn  it  in  all  directions. 

4.  The  Coats  of  the  Eye. — The  eye  is  composed  mostly 
of  membranes  and  transparent  fluids.  The  outer  coat 
consists  of  two  parts,  a  transparent  circular  part  in  front 
called  the  cor-ne-a,  which  appears  to  fit  like  a  watch  crys- 
tal into  the  remaining  part,  which  is  called  the  scle-rot-ic 
coat.  The  part  of  this  which  we  can  see  we  call  the 
"  white  of  the  eye."  It  is  a  very  dense,  tough  membrane, 
elastic,  but  firm  enough  to  give  a  globular  shape  to  the 
eye.  Just  inside  of  the  sclerotic  coat  is  the  cho-roid  coat. 
It  consists  of  a  network  of  fine  blood  vessels  and  pigment 
of  dark  coloring  matter.  A  little  way  back  of  the  cornea 
is  a  circular  curtain  with  a  round  hole  in  the  center.  It 
is  called  the  i-ris  and  the  hole  is  called  the  pu-pil.  The 
iris  is  of  different  colors  in  different  persons.  When  we 
speak  of  the  color  of 
a  person's  eyes,  we 
mean  the  color  of  the 
iris.  Just  inside  the 
choroid  membrane  is 
the  retina,  and  the 
space  enclosed  by 
these  membranes  con- 
tains three  transpar- 
ent substances  called, 
respectively,  the  vit- 
reous humor,  the  crys- 
talline lens,  and  the 
aqueous  humor. 


FIG.  24.  — A  SECTION  OF  THE  HUMAN  EYE. 

A,  Cornea  ;  B,  Aqueous  humor  ;  (7,  Pupil ; 
D,  Iris  ;  E,  Crystalline  lens ;  K,  Vitreous 
humor  ;  L,  Optic  nerve  ;  F,  Sclerotic ; 
G,  Choroid ;  H,  Retina. 


5.    The  Ret-i-na.  —  This  is  the  most  important  part  of 
the  eye,  for  it  is  no  other  than  the  expansion  of  the  optic 


124  PHYSIOLOGY  FOK  BEGINNERS. 

nerve,  which  produces  the  sensation  of  light  and  vision. 
It  consists  of  ten  layers  of  variously  shaped  cells  and 
fibers.  One  of  these  layers  is  called  Jacob's  membrane, 
and  consists  of  numerous  little  rods  and  cones,  which 
appear  to  be  the  real  terminations  of  the  nerve  and  the 
part  essential  to  vision.  These  little  rods  and  cones  are 
not  more  than  one  ten-thousandth  part  of  an  inch  in 
diameter,  and  it  has  been  estimated  that  there  are  as 
many  as  a  million  in  a  space  of  one-tenth  of  an  inch 
square. 

6.  The  Humors  of  the  Eye.  —  The  transparent  parts  of 
the  eye  are  called  humors.     Just  behind  the  iris  is  the 
most  dense  of  these  humors.     It  is  called  the  crystalline 
lens.     It  is  a  solid  body,  yet  compressible  and  elastic.     It 
is  in  the  shape  of  a  double  convex  lens,  and  is  the  prin- 
cipal means   of  converging  the  rays  of  light  upon  the 
retina.     In  front  of  the  iris,  between  the  crystalline  lens 
and  cornea,  is  a  transparent  watery  fluid  called  the  aque- 
ous humor.     The  larger  space  behind  the  crystalline  lens 
is    filled    with  a  thick,  jelly-like,  transparent   substance, 
called  the  vitreous  humor.     These  three  transparent  parts 
of  the  eye  act  as  a  compound  lens,  the  purpose  of  which 
is  to  converge  the  light  upon  the  retina,  and  form  a  pict- 
ure or  image  of  the   objects   from   which   the   light   is 
reflected. 

7.  The  Pupil  of  the  Eye.  —  This  round  hole  in  the  iris 
is  for  the  purpose  of  regulating  the  amount  of  light  neces- 
sary to  form  the  image  on  the  retina.     When  the  light  is 
very  bright,  the  pupil  grows  smaller ;  and  when  it  is  les- 
sened, the  pupil  gets  larger.     This  change  in  the  size  of 
the  pupil  is  caused  by  muscular  fibers  in  the  iris. 


HOW   WE    SEE.  125 

LESSON  42. 
How  We  See. 

i.  The  Eye  is  a  Camera  Obscura.  — If  a  small  hole  be 
made  in  the  side  of  a  box,  and  you  hold  it  before  some 
strongly  lighted  object  and  look  down  in  the  box,  with 
your  head  covered  with  a  cloth  so  as  to  shut  out  all  light 
except  what  comes  through  the  hole,  you  will  see  an  in- 
verted image  of  the  object  on  the  inside  of  the  box. 
This  is  a  camera  obscura  (dark  room).  If  the  hole  be 
enlarged,  it  will  be  necessary  to  place  a  lens  in  the  open- 
ing to  converge  the  rays  of  light,  or  there  will  be  no 
image.  If  the  inside  of  the  box  be  painted  black,  the 
effect  will  be  much  better.  This  is  because  the  rays  of 


FIG.  25.  —  THE  IMAGE  ON  THE  RETINA. 

light  which  strike  the  sides  of  the  bpx  are  absorbed  by 
the  black  surface,  and  not  reflected  again  on  the  image. 

Now  let  us  see  how  the  eye  compares  with  the  camera 
obscura.  The  cornea  admits  the  light  to  the  chamber. 
The  iris  regulates  the  amount  of  light.  The  retina  is  the 
screen  or  surface  upon  which  the  image  falls.  The  trans- 
parent parts  of  the  eye  form  an  adjustable  lens,  which 
converges  the  rays  of  light  and  makes  the  image  fall 
upon  the  retina.  The  dark  colored  choroid  coat  absorbs 


126 


PHYSIOLOGY    FOR   BEGINNERS. 


the  indirect  rays  of   light   so  that   they   are   not   again 
reflected  upon  the  image. 

2.  The  Picture  on  the  Retina.  —  The  image  or  picture 
which  falls  on  the  retina  is,  in  some  way  difficult  for  us 
to  understand,  conveyed  to  the  mind  so  that  we  see  the 
objects  which  form  the  image  in  their  proper  position  and 
size. 

3.  Accommodation.  —  By  this  term  is  meant  the  adjust- 
ing of  the  eye  for  distinct  vision  at  different  distances. 
In  the  camera  obscura,  there  must  always  be  a  certain 
relation  between  the  distances  of  the  object,  the  lens,  and 
the  image  of  the  object.     In  the  eye  there  is  no  arrange- 
ment for  changing  the  distance  between  the  lens  and  the 
screen  which  receives  the  image,  but  the  crystalline  lens 
has  the  power  of  expansion,  so  that  it  becomes  more  con- 
vex;   and     this    change    in    convexity 
produces  the  same  result  as  if  a  change 
in  distance  were    made,    for  the   more 
convex  the  lens  the  nearer  its  focus,  or 
the  point  where  the  rays  of  light  form 
an   image.       This    power    in   the    lens 
of   the  eye  to  change  its  convexity  to 
suit    objects    at    different    distances   is 
called  accommodation. 

FIG.    26.  —  COMPOUND  _  .  .  .  _     .,  .  _ 

LENS  FOR  CORRECTION      4»    Correction  of  Defects  in  the  Lenses 
?MA?EEFECTS  IN  THE  of    the    Eye.  — In    common    lenses    or 
magnifying  glasses,  there    is  an  indis- 
tinctness of  image  and  a  slight  amount  of  color  in  the 
image  produced.     In  the  most  perfect  instruments  these 
defects  are  corrected  by  using  two  kinds  of  glass  in  the 
lens,  of  different  degrees  of  density.     In  the  eye  a  similar 


HOW    WE    SEE.  127 

arrangement  is  seen,  and  the  result  is  a  perfect  image  of 
all  objects. 

5.  Near-sightedness. — A   perfect   or   normal  eye  can 
adjust  itself   for  all  distances  beyond  five  inches.     But 
there  are  some  eyes  in  which  the  lens  refracts  too  much, 
and  the  focus  of  the  rays  is  not  on  the  retina  but  in  front 
of  it,  except  when  looking  at  very  near  objects.     Such 
persons  are  said  to  be  near-sighted.     They  can  be  enabled 
to  see  distant  objects  by  wearing  concave  spectacles,  which 
throw  the  image  back  to  the  retina. 

6.  Far-sightedness.  —  This  defect  in  eyes  is  the  oppo- 
site of  near-sightedness.     The  person  can  see  well  enough 
at  a  distance,  but  not  near  objects.     It  is  corrected  by 
wearing  convex  spectacles. 

7.  Old-Sightedness.  —  This   is    not   the   same   as   far- 
sightedness, although  the  results  are  the   same.     In  this 
case  there  is  an  inability  to  adjust  the  eye  to  near  and  far 
objects,  and  as  the  eye  at  rest  is  naturally  adjusted  to  dis- 
tant objects  they  can  only  see  well  at  a  distance.     This 
occurs  in  old  age,  hence  the  name.     Such  persons  must 
wear  convex  glasses  when   reading   or   examining   near 
objects. 

8.  Color-blindness.  —  Some  persons  cannot  distinguish 
colors  readily,  mistaking  red  for  green,  and  so  on.     Such 
persons  are  said  to  be  color-blind. 


128 


PHYSIOLOGY    FOR   BEGINNERS. 


LESSON  43. 
The  Ear. 

i.  The  External  Ear.  —  The  part  we  see  projecting 
from  the  outside  of  the  head,  and  which  we  usually  call 
the  ear,  is  comparatively  of  little  use  in  man,  as  he  can 
hear  quite  well  if  it  be  cut  off.  It  doubtless  aids  a  little 
in  collecting  the  sound.  It  is  composed  of  cartilage  and 
skin.  In  the  bottom  of  this  part,  which  is  called  the 
pinna,  is  a  tube  which  extends  inward  to  the  middle  ear. 


FIG.  27. — SECTION  OF  THE  EAR. 

a,  Pinna ;    6,  Semicircular  canals  ;  c,  Auditory  canal ;  e,  Bones  of  the  ear ; 
/,  Cochlea ;  0,  Tympanic  membrane  ;  i,  Eustachian  tube  ;  k,  Tympanum. 

It  is  called  the  auditory  canal.  It  is  partly  in  the  skin 
and  partly  in  the  temporal  bone,  but  is  lined  throughout 
with  a  thin  skin  which  contains  in  its  inner  part  glands 
which  secrete  the  ear-wax. 

2.    The  Middle  Ear  or  Tympanum. — At  the  bottom  of 
the  auditory  canal  is  an  irregular  cavity  separated  from 


THE    EAR.  129 

the  canal  by  a  membrane,  called  the  Tympanic  membrane. 
A  tube  leads  from  the  tympanum  to  the  pharynx,  called 
the  Eustachian  tube.  It  permits  air  to  enter  the  tym- 
panum. The  tympanum  is  lined  with  mucous  mem- 
brane. 

3.  The  Bones  of  the  Ear. — Across  the  cavity  of  the 
tympanum,   extending  from  the  tympanic  membrane  to 
the  opening  of  the  internal  ear, 

is  a   chain   of    bones,   not  much  \     \ 

larger  than  heads  of  pins;  but 
they  are  very  important  aids  in 
hearing.  The  one  attached  to  the 
tympanic  membrane  is  called  the 
mal-le-us  (hammer).  The  one  next 
to  this  is  the  in-cus  (anvil).  The 
next  one  joins  the  incus  to  the 

•     ,  -i  T   •          -n     -i    .-,  FIG.   28. — THE  BONES  OF  THE 

internal  ear,  and  is  called  the  sta-  EAR. 

pes      (stirrup).        Although      these  M,  Malleus ;  7,  Incus ;  8,  Stapes. 

bones  are  exceedingly  small,  each 

one  is  joined  to  the  other  by  ligaments,  cartilage,  and 

synovial  membrane,  the  same  as  in  other  joints.     They 

move  easily  when  a  sound  wave   strikes  the  tympanic 

membrane,  and  communicate  the  motion  to  the  internal 

ear. 

4.  The  Internal  Ear,  or  Labyrinth.  —  We  now  come  to 
describe  the  most  important  part  of  the  ear,  the  place 
where  the  sound  waves  are   converted  into  impressions 
made  upon  the  nerve  of  hearing  and,  through  it,  upon  the 
brain  and  mind.      The  internal  ear  is  a  very  curious  cav- 
ity.    It  consists  first  of  a  cavity  in  the  bone,  which  has 
three  parts,  (1)   the  vestibule,  or  entrance,  (2)  the  semi- 
circular canals,  three  loop-like  channels,  and  (3)  the  coch- 


130          PHYSIOLOGY  FOR  BEGINNERS. 

lea,  a  winding  cavity  very  much  like  the  interior  of  a 
snail  shell.  This  curious  cavity  is  lined  with  a  serous 

membrane,  which  secretes  a  fluid 
called  the  per-i-lymph.  In  this 
fluid  floats  a  bag  of  membrane 
which  is  nearly  the  shape  of  the 
labyrinth.  This  bag  contains  a 
watery  fluid  called  en-do-lymph. 

FIG.  29.  —  THE  LABYRINTH.  ^  . 

The    auditory    nerve    ends    in 

branches  which  are  spread  out  in  the  labyrinth,  one  branch 
ending  in  a  great  number  of  little  rods  called  rods  of 
Corti. 

5.  Having  described  the  parts  (Anatomy)  of  the  ear,  in 
the  next  lesson  we  will  explain  the  function  of  hearing 
(Physiology). 


Lesson  44. 
How  we  Hear. 

1 .  What  is  Sound  ?  —  Sound  is  a  vibration  or  wave 
motion  of  matter,  either  solid,  liquid,  or  gaseous,  which  is 
capable  of  producing  a  sensation  through  the  auditory 
nerve.     Usually  the  sound  comes  to  our  ears  through  the 
air,  but  air  is  not  essential  to  sound  or  hearing. 

2.  Use  of  the  External  Ear.  — The  sound  waves  passing 
through  the  air  are  conveyed  through  the  auditory  canal, 
and  strike  the  tympanic  membrane.     The  pinna  in  man 
helps  a  little  to  collect  the  waves  and  direct  them  into 
the  canal.     In  many  of  the  lower  animals  it  is  very  im- 
portant.    You  have  observed  how  horses  and  rabbits,  and 


HOW    WE    HEAR.  131 

many  other  animals,  turn  their  ears  in  the  direction  of 
the  sound. 

3.  The  Use  of  the  Tympanic  Membrane.  —  This  mem- 
brane stretches   like    the  head   of   a  drum  between   the 
external  and  middle  ear.     When  a  wave  of  sound  strikes 
it,  vibrations  are  produced,  which  are  communicated  to  the 
chain  of   bones.      This  membrane  is  very  sensitive  and 
vibrates  easily  when  struck   by  sound  waves.     A   tiny 
muscle  serves  to  put  it  on  the  stretch  and  makes  it  more 
sensitive. 

4.  The  Use  of  the  Little  Bones.  —  The  tiny  bones  of 
the  ear  are  nicely  balanced  upon  each  other,  and  being 
attached  to  the  tympanic  membrane   they   convey   the 
motion  of  the  membrane  to  the  liquid  of  the  internal  ear, 
which  is  only  separated  from  the  stapes,  or  last  bone,  by 
a  thin  membrane  stretched  across  an  oval  opening  in  the 
bony  cavity  of  the  tympanum. 

The  fluids  and  membranes  in  the  labyrinth  are  set  in 
vibration  by  the  chain  of  bones,  and  this  vibration  affects 
the  terminations  of  the  auditory  nerve.  This  nerve  con- 
veys the  impression  to  the  brain,  and  it  is  there  received 
and  produces  in  the  mind  the  sensation  we  call  sound. 
If  you  were  to  touch  the  auditory  nerve,  you  would  feel 
no  pain,  but  would  hear  a  sound.  If  you  were  to  touch 
the  optic  nerve  you  would  see  a  flash  of  light.  These 
nerves  have  each  a  peculiar  power. 

5.  The  Eustachian  Tube. — As  mentioned  in  last  lesson, 
this  tube  admits  air  to  the  middle  ear.     This  is  important, 
for,  if  there  were  not  air  on  both  sides  of  the  membrane, 
it  could  not  vibrate.     It  is  necessary  also  that  the  air  be 
frequently  changed  so  that  it  may  remain  of  the  same 
density.    Every  time  a  person  swallows,  a  little  air  passes 


132  PHYSIOLOGY    FOE    BEGINNERS. 

up  the  Eustachian  tube.  It  permits  the  mucus  also  to 
drain  away  from  the  tympanum.  Also  when  there  is  a 
powerful  sound  and  the  membrane  is  forcibly  pressed  in, 
the  air  can  pass  down  the  tube  and  relieve  the  pressure. 

6.  The  Use  of  the  Ear-wax.  —  This  peculiar,  sticky, 
and  bitter  substance  serves  the  purpose  of  keeping  the  ear 
clean  and  keeping  out  insects.  It  repels  insects  by  its 
sticky  and  bitter  nature  and  keeps  the  ear  clean  by  catch- 
ing the  dust  and  drying  up  and  falling  off  in  scales, 
carrying  the  dirt  with  it. 


LESSON  45. 
Smell,  Taste,  and  Touch. 

1.  The  Nasal  Cavities.  — These  are  two  irregular  cavi- 
ties in  the  nose.    The  openings  in  front  are  called  the  nos- 
trils ;  and  those  at  the  back,  leading  to  the  pharynx,  are 
called  the  posterior  nares.    The  bony  walls  of  these  cavities 
are  very  irregular  and  are  covered  with  mucous  membrane. 
These  cavities  serve  to  conduct  air  to  the  lungs  and  are 
the  special  seat  of  the  sense  of  smell. 

2.  The  Olfactory  Nerve.  —  This  is  the  special  nerve  of 
smell.     It  arises  in  the  front  part  of  the  cerebrum  and 
passes  down  through  the  ethmoid  bone,  there  being  about 
twenty  branches  which  then  spread  out  through  the  mu- 
cous membrane. 

3.  The  Sensation  of  Smell.  —  Odorous  particles  of  mat- 
ter passing  into  the  nostrils  affect  the  olfactory  nerve  and 
give  rise  to  the  peculiar  sensation  of  smell.     These  odor- 
ous particles  must  be  in  a  gaseous  state.     If  a  perfumed 


SMELL,    TASTE,    AND    TOUCH.  133 

liquid  be  placed  in  the  nostrils  and  the  air  excluded,  there 
is  no  smell. 

4.  The  Organs  of  Taste.  —  The  mucous  membrane  of 
the  upper  surface  of  the  tongue,  and  the  back  part  of  the 
mouth,  contain  the  endings  of  the  nerves  which  give  rise 
to  the  sense  of  taste.     The  tongue  is  a  muscular  organ 
covered  with  mucous  membrane.     On  its  upper   surface 
are  a  number  of  little  elevations  called  papillce.     These 
papillae  contain  the  terminations  of  the  nerves  of  taste. 
Bitter  substances  are  tasted  most  strongly  by  the  back 
part  of  the  tongue,  sweet  substances  by  the  tip,  and  sour 
substances  by  the  sides  or  edges  of  the  tongue.     A  sub- 
stance cannot  be  tasted  unless  it  is  in  a  liquid  form.     You 
taste  sugar  or  candy  which  is  not  liquid,  but  not  until 
the  moisture  of  your  mouth  has  dissolved  the  sugar. 

5.  The  Sense  of  Touch.  — The  sense   of  touch  is  the 
power  of  distinguishing  the  shape,  texture,  and  solidity  of 
objects  by  contact  with  the  skin  or  mucous  membrane  of 
the  body.     This  power  is  much  the  greatest  in  the  inner 
side  of  the  ends  of  the  fingers.     In  cases  where  the  sight 
has  been  lost,  the  fingers  become  by  practice  much  more 
sensitive.     Blind  persons  are  enabled  to  read  by  means  of 
raised  letters,  and  can  tell  quite  accurately  the  form  and 
texture  of  objects  by  the  sense  of  touch  alone.     The  nerves 
of  general  sensation  in  the  skin  have  special  terminations 
in  the  papillae  of  the  skin.     These  are  supposed  to  be  the 
special  organs  of  touch. 

6.  General  Sensations.  — We  speak  of  sight,  hearing, 
smell,  taste,  and  touch  as  the  five  special  senses.     Besides 
these  we  have  other  sensations,  which  may  be  called  gen- 
eral sensations ;  among  these  is  the  sensation  of  tempera- 


134  PHYSIOLOGY    FOE  BEGINNERS. 

ture,  by  which  we  can  tell  within  certain  limits  whether  a 
body  is  hot  or  cold,  warm  or  cool.  Great  heat  or  cold 
produces  the  sensation  of  pain.  We  are  apt  to  be 
deceived  by  this  sensation,  for  when  an  object  is  a  good 
conductor  of  heat  it  carries  away  the  heat  of  the  body 
rapidly,  and  will  when  cooler  than  the  body  feel  cooler 
than  it  really  is,  and  when  warmer  than  the  body  will 
impart  its  heat  to  the  body  and  thus  feel  warmer  than  it 
really  is. 

Hunger,  thirst,  and  fatigue  are  general  sensations.  Pain 
is  a  general  sensation  which  is  very  useful  to  us.  If  it 
were  not  for  pain  to  warn  us  of  danger,  we  might  be  con- 
tinually injuring  some  part  of  the  body.  We  are  able  to 
judge  of  the  weight  of  an  object  by  holding  it  in  the 
hands.  This  is  not  the  same  as  touch,  for  we  need  not 
permit  the  object  to  come  in  contact  with  the  body,  and 
yet  judge  quite  accurately  concerning  its  weight  or  the 
amount  of  pressure  it  exerts..  This  is  sometimes  called 
the  muscular  sense. 


LESSON  46. 
Care  of  the  Sense  Organs. 

1.  The  Eye  requires  especial  care  if  we  would  preserve 
its  usefulness  through  life.     It  is  easily  injured  by  dust, 
smoke,  and  irritating   gases,  overwork,  insufficient  or  too 
strong  light,  and  from  other  causes. 

2.  When  some  solid  object  gets  into  the  eye,  do  not  rub  it, 
for  that  causes  further  irritation.     Make  an  effort  to  keep 
the  eyelid  open  for  a  few  seconds.     The  tears  will  accu- 
mulate and  probably  wash  the  object  to  the  inner  corner, 


CARE  OF  THE  SENSE  ORGANS.  135 

where  it  may  be  seen  and  removed.  If  this  fails,  blow 
the  nose  forcibly,  at  the  same  time  closing  the  nostril  on 
the  opposite  side.  If  these  means  fail,  let  some  person 
roll  the  eyelid  over  a  pencil  and  look  for  the  object, 
removing  it  with  the  corner  of  a  handkerchief. 

3.  Do  not  put  medicine  in  the  eyes  without  the  advice  of 
a  physician.     Bathing  them  with  lukewarm  or  cool  water 
will  often  relieve  the  irritation  and  do  no  harm. 

4.  In  reading  or  studying  do  not  sit  facing  the  light,  but 
so  that  it  comes  over  the  left  shoulder  and  falls  on  the  book. 
A  lamp  should  be  bright  and  steady.     The  electric  arc 
light  is  too  powerful  for  reading. 

5.  Reading  small  type,  on  dirty  colored  paper  and  in  a 
poor  light  is  bad  for  the  eyes.     So  is  reading  in  a  car  or 
carriage  when  in  motion,  if  continued  any  length  of  time. 
Do  not  read  while  lying  down. 

6.  The  eyes  need  rest.     They  become  weary  by  being 
used  too  long  at  a  time  looking  at  objects  at  the  same 
distance.     Whenever    we   look   at   a  distant    object,  the 
muscles  which  adjust  the  eye  are  at  rest,  and  when  we 
look  at  near  objects  they  are  in  a  state   of  contraction. 
When  reading,  one  should  frequently  raise  the  eyes  off  the 

page  and  for  a  second  or  two  look  at  some  distant  object. 
This  gives  the  eye  the  needed  rest.     The  eyes  should  not  be 
used  much  when  convalescing  from  sickness.     They  may  be 
permanently  injured  in  this  way. 

7.  Tobacco  smoke  is  injurious  to  the  eyes,  especially  that 
of  cigarettes.     The  bad  effect  of  tobacco  on  the  nervous  sys- 
tem must  necessarily  affect  the  eyes  to  some  extent.     The 
eyes  of  the  drunkard  are  never  clear  and  bright,  but  blurred 
and   bloodshot  from   the  increased   blood  pressure  in   the 
capillaries. 

8.  The  ear  is  not  so  easily  injured,  perhaps,  as  the  eye, 


136  PHYSIOLOGY   FOE   BEGINNERS. 

but  certain  rules  should  be  observed  in  regard  to  taking 
proper  care  of  it.  The  ear  is  sensitive  to  cold  winds,  but 
the  wearing  of  ear  muffs  is  not  to  be  recommended,  as 
they  are  too  compact  and  keep  the  auditory  canal  too  warm, 
and  thus  render  it  more  sensitive  to  cold  when  they 
happen  to  be  left  on0.  A  light  shawl  thrown  loosely  over 
the  head  should  be  used  when  the  wind  is  strong  and 
very  cold.  A  bit  of  cotton  placed  loosely  in  the  ear  is 
good  in  such  cases.  In  snowballing  there  is  risk  of 
snow  being  forcibly  driven  into  the  ear,  causing  serious 
trouble. 

9.  The  ear-wax  should  not  be  removed  with  an  ear- 
spoon   or   any   similar    instrument   unless   unnatural   in 
quantity  or  nature,  and  in  such  cases  a  physician  should 
be  consulted.     To  keep  the  ear  clean  use  only  a  wet  cloth 
over  the  end  of  the  finger.    Never  pick  the  ear  with  a  pin, 
knitting-needle,  or  any  similar  instrument. 

10.  Very  loud  sounds  made  close  to  the  ear  may  cause 
deafness  l>y  rupturing  the  tympanic  membrane. 

11.  Children  sometimes  are  so  foolish  as  to  put  peas, 
beans,  cherry  seeds,  or  the  like  in  their  own  or  a  com- 
panion's ears.     In  such  cases  they  are  often  difficult  to  get 
out  and  may  cause  serious  trouble.     There  need,  however, 
be  no  immediate  cause  for  alarm,  as  the  injury,  if  any,  can- 
not come  unless  it  remains  a  long  time.     Turn  the   ear 
down  and  tap  the  head  gently  on  the  other  side.     If  it 
does  not  come  out,  use  a  syringe  and  a  little  warm  water. 
If  these  means  fail,  send  for  a  physician  who  can  extract 
it  with  proper  instruments. 

12.  The  sense  of  taste  is  apt  to  be  blunted  by  constant 
use  of  very  highly  seasoned  and  very  hot  foods  and  drinks. 
The  confirmed  drunkard  has  lost  the  sense  of  taste  in  a 
great  measure. 


ALCOHOL  AND  ITS  EFFECTS.  137 

13.  All  alcoholic  drinks  and  tobacco  have  an  injurious 
effect  on  the  special  sense  organs,  through  their  effects  on  the 
nervous  system  in  general. 


LESSON  47. 
Alcohol  and  its  Effects. 

1 .  What  is  Alcohol  ?  —  Alcohol  is  a  substance  which 
does  not  exist  in  nature,  but   is   the  product  of  certain 
chemical  changes  on  sugar.     Under  certain  conditions  of 
heat  and  moisture,  germs  of  a  microscopic  plant  grow 
and  reproduce  themselves  in  sugar,  and  convert  the  sugar 
into  alcohol  and  carbon  dioxide.    This  change  is  called 
fermentation.      Sugar  can  in  a  similar   manner  be  pro- 
duced from  starch.     Therefore  any  substance  containing 
either  sugar  or  starch  can  by  fermentation  be  used  for  the 
production  of  alcohol. 

2.  Uses  of  Alcohol.  —  Alcohol  is  a  very  useful  substance 
in  its  proper  place.     It  burns  without  smoke,  producing 
intense  heat.     This  makes  it  useful  in  many  ways  in  the 
arts.     It  dissolves  resins  and  oils,  and  is  useful  in  prepar- 
ing varnishes  and  paints.    It  hardens  and  preserves  animal 
and  vegetable  substances,  hence  is  useful  to  the  microscopist 
and  students  of  Botany  and  Physiology.     In  medicine  it 
has  many  and  important  uses.      Certain  medicinal  sub- 
stances could  not  be  extracted  from  plants  without  it ;  and, 
in  a  proper  state  of  dilution,  it  is  useful  as  a  medicine  in 
the  hands  of  a  skillful  physician. 

3.  Summary  of  the  Effects  of  Alcohol  on  the  Human 
Body.  —  In  the  preceding   lessons  we   have  given   brief 


138  PHYSIOLOGY    FOR   BEGINNERS. 

statements  of  the  effects  of  alcohol  on  the  various  organs; 
we  here  repeat  them  in  a  more  compact  form :  — 

1.  On  the  Bony  Framework.  —  The  growth  of  bones  is 
checked  by  the  injury  done  to  the  digestive  and  circula- 
tory organs,  whereby  the  supply  of   nourishment  is  cut 
short.     Dwarfs  may  be  made  of  children  by  giving  them 
alcoholic  drinks  when  quite  young. 

2.  On  the  Muscles.  —  The  power  of  muscles  to  act  in 
obedience  to  the  will  is  impaired.     The  drunken  man  can- 
not walk  straight,  cannot  talk  correctly,  and  sees  double, 
because   he   cannot   control   the    muscles   used  in   these 
actions. 

3.  On  the  Digestive  Organs.  —  Alcohol  has  the  effect  of 
removing  water  from  the  lining  of  the  stomach  and  intes- 
tines,   and  thus  tending  to   thicken  it  and  diminish  its 
power  of   absorption.      It  hardens   the   liver   and  other 
glands. 

4.  On  the  Circulatory  Organs.  —  The  blood  vessels  are 
distended  and  overworked,  in  time.     The  heart  is  weak- 
ened by  overwork  induced  by  alcoholic  excess. 

5.  On  the  Respiratory    Organs.  —  The  power  of  puri- 
fying the  blood  is  diminished,  and  the  mucous  membrane 
of  the  respiratory  organs  is  injuriously  affected. 

6.  It  causes  rapid  loss  of  heat,  hence  weakens  the  body 
when  it  is  exposed  to  great  cold.     It  is  a  well-known  fact 
that  among  travelers,  explorers,  and  soldiers,  who  have 
been  obliged  to  expose  themselves  to  extreme  cold,  those 
who  were  temperate  stood  the  effects  of  the  cold  better 
than  those  who  drank. 

7.  On  the  Nervous  System.  —  The  power  of  the  nerves 
over  the  various  organs  of  the  body  is  weakened  or  dis- 
turbed ;  hence,  through  the  nervous  system,  alcohol  affects 


ALCOHOL    AND    ITS    EFFECTS.  139 

all  the  organs  of  the  body.  It  hardens  nerve  tissue  and 
leads  to  insanity. 

8.  On  the  Organs  of  Special  Sense.  —  By  its  general 
effects  on  the  nervous  system  alcohol,  when  used  for  a 
long  time,  affects  all  the  special  senses. 

Dr.  N.  S.  Davis,  a  noted  physician  of  Chicago,  in  a 
recent  address  said  :  "  By  all  chemists,  and  other  scientific 
men,  it  is  classed  as  an  active  poison  capable  of  destroying 
life  when  taken  in  sufficient  doses;  and,  if  taken  pure 
or  undiluted,  it  destroys  the  vitality  of  the  tissues  with 
which  it  comes  in  contact  as  readily  as  creosote  or  carbolic 
acid.  When  largely  diluted  with  water,  as  it  is  in  all 
the  varieties  of  fermented  and  distilled  liquids,  and  taken 
into  the  stomach,  it  is  rapidly  imbibed  or  taken  up  by 
the  capillary  vessels  and  carried  into  the  venous  blood, 
without  having  undergone  any  digestion  or  change  in  the 
stomach." 

4.  Social  and  Moral  Effects  of  Alcohol.  —  In  a  com- 
munity where  the  drinking  habits  are  not  under  restraint, 
the  social  and  moral  condition  of  the  people  is  of  a  low 
grade.  Drunken  men  are  generally  quarrelsome,  and 
fights  and  murders  are  common  where  there  is  much 
drinking.  A  love  of  drink  and  its  attendant  amusements 
excludes  higher  and  more  intellectual  sports  and  occu- 
pations. Alcohol,  moreover,  when  used  for  a  long  time 
to  excess,  actually  impairs  a  man's  moral  sense.  It  pro- 
duces a  kind  of  insanity  peculiar  to  itself.  When  once 
a  man  becomes  a  confirmed  drunkard,  he  rarely  reforms. 
He  may  sign  a  solemn  pledge  and  even  exhort  others  to 
reform,  but  in  spite  of  all  inducements  and  persuasions 
of  friends  he  is  apt  to  return  to  his  drink,  having  lost  all 
moral  power  to  abstain  from  it.  Tills  should  be  a  solemn 


140  PHYSIOLOGY    FOR    BEGINNERS. 

lesson  to  those  who  have  not  formed  the  habit.  The  first 
drink  leads  to  more.,  and  the  end  may  ~be  a  horrible  one. 
Bad  habits  are  nearly  always  formed  in  youth.  If  every 
one  could  ~be  persuaded  to  abstain  entirely  from  all  intoxi- 
cating liquors  and  tobacco,  until  past  thirty  years  of  age, 
the  probabilities  are  that  there  would  not  be  one  drunkard 
where  there  are  now  a  hundred. 


LESSON  48. 
Tobacco  and  Its  Danger. 

1.  The  Extent  of   its  Use. — There  is  not  a  race  of 
people  on  the  face  of  the  earth  that  does  not  use  tobacco. 
Thirty  years  ago  it  was  estimated   that    4,480,000,000 
pounds   of   tobacco  were  used  annually,  and  since  that 
time  its  use  has  been  increasing.     This  is  no  argument 
in  favor  of   its  value   to  the  human  race.     The  world 
might  easily  get  along  without  tobacco. 

2 .  Its  Effects  on  the  Human  Body.  —  There  are  many 
persons  who  apparently  are  not  affected  by  the   use  of 
tobacco.     After  middle  age  it  often  seems  to  be  beneficial ; 
at  least,  it  is  injurious  in  a  less  number  of  cases.     It  is 
undoubtedly  injurious  to  young  persons  while  the  body 
is  growing.     The  testimony  of  physicians  and  scientific 
men  is  almost  unanimous  on  this  point. 

In  many  cases  the  chewing  and  smoking  of  tobacco 
causes  dyspepsia  of  the  worst  form.  In  chewing,  the 
salivary  glands  are  excited  when  there  is  no  food  to  be 
digested,  and  the  saliva  is  thus  produced  in  excess.  The 
glands  are  thus  weakened  by  overwork,  and  the  quality  of 


TOBACCO    AND    ITS    DANGER.  141 

the  saliva  is  impaired.  Smoking  tends  to  produce  dys- 
pepsia by  its  effects  on  the  nervous  system. 

There  is  no  doubt  that  tobacco  injuriously  affects  the 
heart  in  a  great  many  cases.  Physicians  recognize  what 
they  call  a  "  smoker's  heart "  or  "  tobacco  heart."  It 
is  a  form  of  fluttering  or  palpitation  of  the  heart,  pro- 
duced by  the  effects  of  tobacco  on  the  nervous  system. 

On  the  nervous  system  itself,  tobacco  often  exerts  an 
injurious  effect,  producing  sleeplessness,  melancholy  spirits,, 
trembling,  headaches,  and  sometimes  disturbance  of  vision. 

3.  Slaves  to  Habit.  — It  is  not  good  to  become  addicted 
to  the  use  of  any  article  of  food,  drink,  or  stimulant,  to  the 
extent  of  feeling  that  one  cannot  get  along  without  it. 
Persons  who  get  into  the  habit  of  using  tobacco  generally 
find  it  very  difficult  to  quit  it,  and  often  find  it  hard  to 
limit  it  in  extent.     The  more  one  uses  of  any  stimulant, 
the  more  the  appetite  demands.     Persons  who  form  habits 
of    using    tobacco    and   alcoholic   drinks  find  themselves 
feeling  miserable  when,  from   any  cause,  they  are  com- 
pelled to  be  without  them.     This  is  certainly  not  a  desira- 
ble condition.     Young  people  should  try  to  form  habits 
of  self-control  of  appetite.     Appetite  is  a  good  thing,  an 
essential  thing,  but,  when  perverted,  becomes  the  ruin  of 
the  body  and  soul.     Learn  to  control  your  appetite.     The 
mind  should  be  the  master  of  the  body,  and  not  the  stom- 
ach or  the  sensations.     Herein  lies  the  true  pleasure  of 
existence,  the  ability  to  control  passion  and  appetite,  and 
make  them  serve  the  uses  of  the  body. 

4.  A  Useless  Habit.  —  One  who  does  not  use  tobacco  feels 
just  as  well  as  one  ivho  does,  and  in  most  cases  he  feels  better 
and  enjoys  life  more.     He  does  not,  at  least,  feel  the  need  of 
tobacco  and  he  is  saved  the  expense,  ivhich  is  no  inconsider- 


142  PHYSIOLOGY  FOR  BEGINNERS. 

able  item.  Old  persons  who  feel  the  need  of  a  mild  stimu- 
lant should  use  coffee  or  chocolate,  and  they  will  have  no 
need  of  tobacco. 


LESSON  49. 
Other  Stimulants  and  Narcotics. 

1.  Definitions.  —  Thus   far    we   have    discussed    only 
alcohol    and   tobacco,   among   the    substances   classed  as 
stimulants  and  narcotics.    By  stimulants  we  are  to  under- 
stand those  substances  which  produce  excitement  or  tem- 
porarily increase  the  forces  of  the  system.     Thus,  alcohol 
makes  the    heart  beat  faster,  the   blood   circulate    more 
freely,  and  produces  a  temporary  increased  action  of  the 
nervous  system ;  and  we  call  it  a  stimulant.     A  narcotic 
is  a   substance  which  tends   to  depress  or   paralyze  the 
forces   of   the  system.     All  stimulants  become  narcotics 
when  used  in  sufficient  quantity  or  continued  for  a  con- 
siderable  time.      Stimulants  add  nothing  to  the  strength, 
but  simply    cause   strength  to  be  exerted.     They  are  like 
the  whip  and  spur  to  the  horse.     They  do  not  increase 
his  strength,  but  excite  him  to  make  greater  effort,  and 
the  result  is  exhaustion  comes  the  sooner. 

2.  Opium.  —  This  is  one  of  the  most  valuable  of  medi- 
cines when  properly  used,  but,  when  taken  merely  for  its 
stimulating  and  narcotic  effects,  it  is  one  of  the  most  danger- 
ous of  drugs.     It  is  a  kind  of  gum,  being  the  dried  and 
thickened  juice  or  milk  of  a  kind  of  poppy.     It  is  grown 
chiefly  in  Persia,  Turkey,  and  India.     It  is  either  chewed 
and   swallowed,   or  smoked  in  a  pipe.      Its  solution  in 
alcohol  is  known  as  laudanum.     Some  who  wish  to  get  its 


OTHER   STIMULANTS    AND    NARCOTICS.  143 

intoxicating  effect  take  it  in  this  form.  A  white  crystal- 
line powder  may  be  extracted  from  opium,  and  is  known 
as  morphine.  It  possesses  all  of  the  intoxicating  proper- 
ties of  opium  in  a  more  condensed  form.  Many  use 
morphine  instead  of  opium. 

3.  Effects  of  Opium.  —  The  first  effects  of  opium  is  a 
pleasurable  or  comfortable  condition  of  the  entire  system. 
Then  a  period  of  stupor  follows  and  a  disposition  to  sleep, 
in  which  there  are  usually  very  extravagant  and  sometimes 
frightful  dreams.    On  recovering  from  the  stupor,  the  body 
is  weak,  the  head  aches,  and  a  very  miserable   feeling  fol- 
lows ;  and  the  victim  of  the  habit  is  not  happy  until  he  has 
taken  another  dose.    When  the  habit  is  once  formed,  the 
person  is  the  most  helpless  slave  imaginable.    It  is  almost 
impossible  for  him  to  break  off  the  habit.     He  loses  his 
will  power ;  and,  besides,  the  abstinence  from  the  drug 
seems  to  produce  a  condition  more  miserable  than  the  drug 
did  in  the  first  place. 

In  time  the  effects  shoiv  plainly  on  the  person.  His  skin 
becomes  yellow,  the  eyes  sunken  and  glassy,  the  body  emaci- 
ated and  bent,  and  the  victim  is  a  hopeless  ivreck  of  hu- 
manity. The  moral  sense  is  destroyed,  and  the  person  will 
not  hesitate  to  lie  and  steal  to  get  possession  of  his  favorite 
drug. 

4.  There  have  been  a  few  cases  where  men  have  cured 
themselves  of  the  habit,  simply  by  great  will  power ;  but 
such  cases  are  the  rare  exceptions.    The  people  of  Turkey, 
India,  and  China  are  especially  addicted  to  the  habit  of 
eating  and   smoking   opium.     The   habit   is   said   to   be 
greatly  on  the  increase  in  the  United  States.     The  habit 
is  a  greater  physiological  crime  than  the  use  of  alcoholic 
liquors,  for  it  more  rapidly  gains  control  of  the  person,  and 


144  PHYSIOLOGY   FOR   BEGINNERS. 

nearly  always  makes  a  physical  wreck  of  the  victim  in  a 
few  years.  Persons  who  suffer  much  from  neuralgia, 
rheumatism,  and  similar  painful  diseases  are  apt  to 
acquire  the  habit  by  using  it  freely  as  medicine.  JVb  one 
should  use  morphine,  opium,  or  laudanum  without  the  advice 
of  a  physician ;  and  even  then  it  will  often  be  better  to  suffer 
pain  for  a  time  than  to  take  the  risks  of  forming  a  habit  of 
using  these  drugs.  Physicians  are  sometimes  uninten- 
tionally the  agents  concerned  in  the  formation  of  such 
habits. 

5.  Indian  Hemp.  —  In  India,  Turkey,  and  Arabia  large 
quantities  of  a  resinous  substance  produced  from  the  hemp 
plant  is  used  as  a  narcotic.     It  produces  a  kind  of  tempo- 
rary insanity,  but  does  not  seem  to  affect  the  circulation 
and  digestion  in  such  a  degree  as  opium  does. 

6.  Coca.  —  This  is  not  the  same  as  cocoa,  from  which 
chocolate  is  made.     The  latter  is  a  comparatively  harm- 
less stimulant,  while  the  coca  possesses  narcotic  properties 
in  the  highest  degree.     It  is  the  leaves  of  a  bush  which 
grows  in  South  America.     It  is  used  by  the  natives  of 
that  country  to  a  great  extent.     Cocaine,  an  extract  from 
it,  is  now  much  employed  in  medicine. 

7.  Betel-nut.  —  This  is  the  seed  of  a  kind  of  palm-tree 
which  grows  in  India  and  the  islands  of  the  Indian  Ocean. 
It  is  chewed  like  tobacco  and  gives  a  deep  red  color  to  the 
saliva  and  to  the  lips  and  teeth.     This  is  considered  very 
ornamental  by  the  natives.     It  is  highly  narcotic. 

8.  Chloroform  and  Ether.  —  These  are  two  very  valu- 
able substances,  used  by  surgeons  to  produce  a  state  of 
insensibility  while  performing  surgical  operations.     Since 
these  substances  have  come  into  use,  many  important  sur- 


WHAT    TO    DO    IN    EMERGENCIES.  145 

gical  operations  are  possible  which  formerly  could  not  be 
performed  without  great  danger  to  life.  Their  proper  use 
has  saved  thousands  of  lives,  but  there  is  no  good  thing 
that  has  not  been  abused  by  mankind.  Many  people, 
knowing  the  great  relief  from  pain  to  be  obtained  by  their 
use,  have  formed  the  habit  of  using  them  for  every  ache 
and  pain;  and  some  get  into  the  habit  of  using  them  as 
others  do  opium  for  the  intoxicating  effects.  We  would 
warn  the  young  person  who  uses  this  look,  to  avoid  all 
substances  which  produce  stimulating  and  narcotic  effects. 
Never  take  any  of  them  without  the  consent  of  a  physician. 


LESSON  50. 
What  to  Do  in  Emergencies. 

1.  Presence  of  Mind.  —  The  first  and  most  important 
thing,  in  all  cases  of  accident  and  sudden  severe  illness,  is 
self-control  on  the  part  of  those  present.     If  one  would 
just  remember  that  screaming,  crying,  and  rushing  around 
madly  does  no  good,  but  excites  the  sufferer  and  takes  up 
valuable  time  which  might  be  used  in  thinking  what  to 
do,  and  in  doing  it. 

2.  Fire.  —  If  a  person's  clothes  get  on  fire,  seize  any 
cloth  or  garment,  as  a  bedquilt,  a  cloak,  a  piece  of  carpet, 
or  a  rug,  and  wrap  him  in  it.     If  this  be  done  fearlessly 
and  quickly,  the  chances  are  that  the  fire  will  be  smothered 
without  serious  injury  to  any  one.     Do  not  wait  for  water, 
as  the  fire  is  put  out  easier  by  smothering  in  this  way. 

3.  Fainting.  —  Never   raise    a  fainting  person.       The 
blood  has  left  the  head,  and  the  prostrate  position  favors 


146  PHYSIOLOGY  FOR  BEGINNERS. 

its  return.  If  one  faints  sitting  in  a  chair,  seize  the  back 
of  the  chair  and  pull  it  down  until  the  head  is  on  a  level 
with  the  feet,  or  lower.  This  simple  operation  may  re- 
store him.  Loosen  the  clothing  about  the  neck  and 
waist,  and  sprinkle  cold  water  in  the  face.  Keep  away 
the  crowd,  as  fresh  air  is  very  important.  In  apoplexy, 
however,  the  unconsciousness  is  due  to  rush  of  blood  to 
the  head.  In  ordinary  fainting  the  face  is  always  pale, 
but  in  an  apoplectic  fit  it  is  apt  to  be  flushed.  An  apoplec- 
tic person  should  be  raised,  the  clothing  loosened,  and  a 
doctor  sent  for  at  once.  Apoplexy  is  not  very  common,  and 
usually  occurs  to  persons  with  short  necks  and  of  heavy 
build.  It  is  most  frequent  in  middle-aged  or  old  people, 
and  those  who  have  been  addicted  to  drink. 

4.  Choking. — Bits  of  bone  or  other  substances  some- 
times become  fixed  in  the  throat  and  produce  a  trouble- 
some cough  or  suffocation.     In  most  cases  a  smart  blow 
on  the  back  between  the  shoulders  will  cause  the  sub- 
stance to  fly  out.     If  this  does  not  avail,  look  in  the  mouth. 
The  object  may  be  seen  and  seized  with  the  fingers  or  a 
pair  of  pincers.     An  emetic  of  ground  mustard  and  warm 
water  may  be  given,  if  the  person  can  swallow. 

5.  Bleeding  of  the  Nose.  —  This  often  amounts  to    a 
serious  trouble.     Holding  the  hands  and  arms  high  above 
the  head  for  several  minutes  has  been  known  to  stop  it. 
The  effort  to  do  this  causes  the  blood  to  flow  more  freely 
to  the  muscles  of  the  arms  and  shoulders,  and  thus  diverts 
it  away  from  the  nose.     Bathe  the  face  and  neck  in  cold 
water.     Pour  a  solution    of   alum  into   the  nostrils.     If 
these  means  fail,  send  for  a  physician.    He  will  be  able  to 
stop  it  by  properly  plugging  the  nostrils. 


WHAT    TO    DO    IN    EMERGENCIES.  147 

6.  Poisons  and  Poisoning.  —  It  is  not  advisable  to  give 
here  a  list  of  poisons  and  antidotes,  as  the  proper  antidote 
would  be  very  likely  to  be  forgotten  when  the  occasion 
required  its  use.  But  there  are  certain  general  princi- 
ples to  be  observed  which  every  one  ought  to  know. 

An  emetic  —  that  is,  some  substance  which  will  produce 
quick  vomiting  —  is  always  proper  when  poison  is  supposed 
to  have  been  swallowed.  The  quickest  emetic  is  a  tea- 
spoonful  of  ground  mustard  in  half  a  pint  of  warm  water. 
If  this  be  not  at  hand,  salt  and  water,  warm  water  in 
large  quantities,  alum  and  warm  water,  or  soapsuds  may 
be  used.  If  these  fail,  push  the  finger  down  the  throat 
as  far  as  possible.  If  nothing  but  cold  water  be  at  hand, 
drink  copiously  of  it  and  then  push  the  finger  into  the 
throat. 

If  the  nature  of  the  poison  be  not  known,  the  emetic 
should  be  given  first.  If  it  is  known,  then  the  emetic  is 
not  improper  if  the  proper  antidote  be  not  known  or  be 
not  at  hand. 

All  alkalies,  such  as  concentrated  lye,  potash,  sal-soda, 
and  ammonia,  are  neutralized  by  acids.  But  only  the 
harmless  acids  may  be  used,  or  they  will  produce  their 
own  poisonibg  if  a  little  too  much  be  used.  The  harmless 
acids  that  may  be  at  hand  are  vinegar,  lemon  juice,  sour 
milk,  and  sour  cider,  and  possibly  cream  of  tartar.  Use 
these  freely. 

All  poisonous  acids,  such  as  sulphuric  acid  or  oil  of  vitriol, 
nitric  acid  or  aqua  fortis,  hydrochloric  acid  or  muriatic 
acid,  acetic  acid,  and  oxalic  acid,  require  as  antidotes  the 
harmless  alkalies.  Those  that  are  often  at  hand  are  chalk, 
magnesia,  soap,  and  lime  water.  If  nothing  else  be  at 
hand,  scrape  the  plaster  from  the  wall,  mix  with  water, 
and  give. 


148  PHYSIOLOGY    FOR   BEGINNERS. 

After  vomiting  has  been  produced  or  the  antidote  given, 
it  is  proper  to  give  any  oily  or  mucilaginous  substance, 
such  as  lard,  cream,  milk,  white  of  egg,  flour  and  water, 
or  starch  and  water.  These  substances  tend  to  prevent 
absorption  of  the  poison  from  the  stomach,  and  also 
soothe  the  irritation  of  the  mucous  coat.  But,  in  case 
phosphorus  is  swallowed,  no  oily  substance  should  be 
used. 

7.  Sunstroke.  —  This  is  a  sudden  prostration  caused  by 
long  exposure  to  excessive  heat,  when  the  body  has  been 
weakened  by  fatigue  or  other  causes.      It  may  occur  to 
persons  who  work  in  the  house  as  well  as  to  those  who  are 
in  the  sun.     Most  cases  occur  in  large  cities,  where  the 
heat  is  greater,  and  where  there  are  more  persons  who  are 
not  accustomed  to  exercising  in  a  heated  atmosphere.     It 
begins  usually  with  dizziness  or  pain  in  the  head,  disturbed 
vision,  and   labored  breathing,  followed  by  unconscious- 
ness.    Sometimes  it  comes  on  very  suddenly.    The  person 
should  be  carried  to  the  nearest  cool,  shady  place.    Loosen 
the  clothing  and  apply  wet  cloths  to  the  head,  and  tur- 
pentine or  mustard  to  the  legs  and  soles  of  the  feet. 

8.  Drowning.  — A  doctor  should  be  called  at  once,  but 
in  the  meantime  the  by-standers  may  do  much  toward 
restoring  life.    Remove  clothing  from  face,  neck,  and  chest. 
Place  the  person  on  the  face,  with  one  arm  under  the  fore- 
head.    This  position  causes  the  tongue  to  fall  forward, 
and  permits  the  water  to  escape  more  freely.     If  breath- 
ing begins,  proceed  to  restore  warmth   by  applying  hot 
flannels  or  cloths  to  the  stomach,  between  the  thighs,  and 
to  the  soles  of  the  feet.     A  little  strong  coffee  or  a  little 
wine  or  brandy  may  be   given.      If  breathing  does  not 
begin,  try  to  induce  it  by  turning  the  body  on  one  side, 


WHAT    TO    DO    IN"    EMEKGENCIES.  149 

tickling  the  throat  and  nostrils  with  a  feather  or  bit  of 
paper,  and  dashing  cold  water  in  the  face.  If  this  does 
not  succeed,  turn  the  body  back  again  on  the  face,  support- 
ing the  chest  on  a  folded  coat  or  something  of  the  kind ; 
then  turn  back  again  on  side,  and  repeat  this  operation 
for  five  minutes. 

If  by  this  time  the  doctor  has  not  arrived,  attempt  arti- 
ficial breathing  by  drawing  the  arms  up  over  the  head, 
then  press  them  firmly  against  the  side  of  the  chest. 
Repeat  this  many  times,  while  others  are  trying  to  produce 
warmth  in  the  manner  described.  Persons  have  been 
restored  after  six  hours  of  apparent  death.  So  do  not 
despair  if  good  results  do  not  appear  in  three  or  four  hours 
of  such  work. 

9.  Freezing.  —  Do  not  take  a  person  who  is  stupefied 
from  exposure   to   cold  into  a  warm  room,  but  remove 
clothes  if  wet,  and  wrap  in  blankets,  and  rub  the  body 
vigorously  with  the  hands,  giving  a  little  warm  tea  or 
coffee  or  weakened  wine.     Make  him  move  about,  if  pos- 
sible, and  bend  and  move  the  limbs  to  increase  the  circu- 
lation.    When  extremities,  as  the  nose,  ears,  or  feet,  are 
frozen,  keep  away  from  the  fire  and  bathe  in  cold  water 
or  rub  with  snow.      Then  apply  sweet  oil  or  lard  and 
wrap  in   flannel.      Extreme   cold  produces   a  feeling   of 
drowsiness.     One  should  guard  against  this.    To  yield  and 
go  to  sleep  is  certain  death.     Keep  in  motion  as  long  as 
possible. 

10.  Broken  Bones,  Dislocations,  and  Sprains.  — A  broken 
bone    may  be   known  by  the  person  not  being  able   to 
raise  the   limb,  by  its  bending  where  there  is   no  joint, 
and  by  the  pain  and  swelling  ;  also  by  hearing  the  broken 
ends  grate  on  each  other  when  moved.     Place  the  person 


150  PHYSIOLOGY    FOR   BEGINNERS. 

in  an  easy  position,  apply  wet  cloths  to  the  limb,  and  send 
for  the  doctor. 

Dislocations  are  known  by  the  unnatural  appearance  of 
the  part,  by  the  pain  and  inability  to  make  all  the  usual 
movements  of  the  limb.  It  is  often  difficult  to  tell  the 
difference  between  a  dislocation  and  a  fracture.  Send  for 
a  physician  if  either  is  suspected. 

Sprains  are  sometimes  more  serious  than  fractures  or 
dislocations.  They  are  frequently  very  painful  and  long 
in  getting  well.  Keep  the  limb  quiet,  and  use  warm  and 
moist  applications ;  warm  vinegar  and  flannel  cloths  are 
excellent. 


INDEX. 


Note  to  the  Teacher.  —  Pupils  should  be  taught  at  a  very  early  age  the  value  of 
an  index  to  a  book.  They  should  never  for  a' moment  think  that  it  is  the  text-book 
they  are  studying,  but  the  subjects  therein  discussed.  There  is  no  better  way  to  im- 
press this  fact  on  their  minds,  and  to  get  them  out  of  the  ruts  of  routine  study,  than 
to  assign  lessons  in  such  a  manner  as  to  compel  them  to  use  the  index.  The  teacher 
may  occasionally  select  certain  words  from  the  index,  writing  them  on  the  black- 
board, leaving  out  the  reference  numbers,  and  require  the  pupils  to  find  these  words 
in  the  index,  to  look  up  the  references  in  the  body  of  the  book,  and  to  study  them  as 
a  lesson.  Practice  in  looking  for  words  in  an  index  and  in  finding  the  subjects  in  the 
text  is  a  very  important  part  of  a  pupil's  training ;  for,  as  he  goes  out  into  the  world 
and  studies  in  libraries,  indexes,  dictionaries,  and  encyclopedias  are  his  only  teachers. 

Note  to  the  Pupil. — In  studying  lessons  assigned  you,  if  you  find  a  subject  not 
clear,  consult  the  index  of  the  book  for  the  important  words,  and  look  up  all  the 
references  there  given.  Some  other  part  of  the  book  may  make  the  point  clear,  or  a 
comparison  of  two  or  more  paragraphs  may  help  you  very  much  to  understand  the 
discussion. 


Abdomen,  38. 
Aducens  nerve,  110. 
Absorption,  49,  100,  102. 
Accommodation,  126. 
Acids,  147. 

Actions  of  muscles,  22. 
"  Adam's  apple,"  83. 
Air,  Composition  of,  88. 

Effect  of  breathing  on,  88. 

Pure,  89. 

Moisture  in,  90. 

Dust  in,  90. 

Draughts  of,  91. 
Air-cells,  85. 
Albinos,  95. 
Albumen,  52. 
Albuminose,  39,  46. 
Albuminous  substances,  51. 
Alcohol. 

Effect  on  muscles,  28. 
on  bones,  15. 
on  digestion,  56. 


Alcohol  —  Continued. 
Effect  on  circulation,  78. 

on  respiration,  92. 

on  nervous  system,  118. 

on  special  senses,  137. 

summarized,  137. 
General  description  of,  137. 
Alimentary  canal,  41. 
Alkalies,  147. 
Anastomosing,  66. 
Anatomy  defined,  1. 
Animal  heat,  50. 
Ankle  joint,  18. 
Aorta,  64. 

Appendix,  Vermiform,  41. 
Aqueous  humor,  124. 
Arachnoid  membrane,  106. 
Arbor  vitse,  108. 
Arm  bones,  13. 
Arteries,  64,  65. 
Articulation,  84. 
Assimilation,  51. 

161 


152 


INDEX. 


Atlas,  12. 

Auditory  canal,  128. 
Auditory  nerve,  110. 
Auricles,  60. 
Automatic  action,  115. 
Axis,  12. 

Bathing. 

Kinds  of  baths,  104. 

Value  of,  103. 
Betel-nut,  144. 
Bicuspid  teeth,  33. 
Bile,  45. 

Bleeding,  78,  146. 
Blood,  Amount  of,  70. 

Composition  of,  70,  71. 

Circulation  of,  102. 

Properties  of,  70. 
Bolus,  37. 
Bones,  Broken,  149. 

Composition  of,  5. 

Covering  of,  8. 

Growth  of,  6,  7. 

Hygiene  of,  14. 

Names  of,  9. 

Number  of,  9. 

Structure  of,  5. 

Uses  of,  8. 

Young  and  old,  6. 
Brain,  Coverings  of,  106. 

Divisions  of,  106. 

Location  of,  105. 

Structure  of,  108. 
Breastbone,  11. 
Breathing,  82. 
Bronchial  tubes,  84. 

Camera  obscura,  125. 
Canaliculi,  7. 
Canine  teeth,  33. 
Capillaries,  64,  69. 
Carbonaceous  foods,  52. 
Carbon  dioxide,  88. 
Cardiac  orifice,  38. 


Carotid  artery,  65. 
Carpus,  13. 
Cartilage,  7,  17. 
Casein,  52. 

Cavities  of  the  heart,  60. 
Cells,  2. 
Cement,  34. 
Cerebellum,  107,  113. 
Cerebrum,  106,  113. 
Cervical  vertebrae,  12. 
Children,  15. 
Chloroform,  144. 
Chocolate,  56,  118. 
Choking,  146. 
Choroid  coat,  123. 
Chyle,  48. 
Chyme,  48. 
Cilia,  84. 
Circulation,  Kate  of,  74. 

Causes  of,  73. 

Exercise  and,  77. 

Cold  and  heat  and,  76. 

Nervous  shocks  and,  77« 

Alcohol  and,  78. 

Tobacco  and,  79. 
Clavicle,  11. 
Cleanliness,  103. 
Clothing,  104. 
Coagulation,  71. 
Coca,  144. 
Coccyx,  12. 
Cochlea,  129. 
Coecum,  41. 
Coffee,  56,  118. 
"Colds,"  91. 
Collar-bone,  11. 
Colon,  41. 

Color-blindness,  127. 
Condiments,  56. 
Conjunctiva,  122. 
Convolutions  of  brain,  107. 
Cooking,  54. 
Corium,  96. 
Cornea,  123. 


INDEX. 


153 


Corpuscles,  70. 
Course  of  the  blood,  72. 
Covering  of  bones,  8. 
Cranial  nerves,  110. 
Cranium,  10. 
Cricoid  cartilage,  83. 
Crystalline  lens,  124. 
Cuneiform  bone,  13. 
Cystic  duct,  45. 

Dandruff,  95. 
Dentine,  34. 
Dental  pulp,  34. 
Derma,  96. 
Diaphragm,  37. 
Digestion,  47. 
Digestive  system,  31. 
Dislocation  of  bones,  149. 
Drinks,  Warm  and  cold,  55. 
Drowning,  148. 
Duodenum,  39. 
Dura  mater,  106. 

Ear,  External,  128,  130. 

Middle,  128. 

Internal,  129. 

Hygiene  of,  135. 

Bones  of,  129,  131. 
Ear-wax,  128,  132. 
Eating,  Regularity  in,  55. 

Frequency  of,  55. 
Elbow  joint,  18. 
Emergencies,  445. 
Enamel,  34. 
Endolymph,  130. 
Epiglottis,  83. 
Esophagus,  36. 
Ether,  144. 
Ethmoid  bone,  11. 
Eustachian  tube,  36,  129,  131. 
Excretion,  100. 
Exercise. 

Alternation  with  rest,  25. 

and  respiration,  92. 


Exercise,  Kinds  of,  27. 

Expiration,  86. 

Eye,  Structure  of,  123. 

Physiology  of,  125. 

Hygiene  of,  134. 
Eyebrows,  121. 
Eyelashes,  121. 

Facial  nerve,  110. 

Fainting,  145. 

Far-sightedness,  127. 

"  Father  of  Medicine,"  1. 

Fats,  51. 

Fauces,  31. 

Femoral  artery,  65. 

Femur,  15. 

Fiber  of  muscle,  22. 

Fibrin,  52. 

Fibula,  14. 

Focus  in  camera,  126. 

Foods,  Classified,  51. 

Quantity,  53. 

Quality,  53. 

and  drinks,  52. 
Fractures  of  bones,  149 . 
Freckles,  95. 
Freezing,  149. 
Frontal  bone,  11. 

Functions  of   different  organs.    See 
under  names  of  organs. 

Gall-bladder,  45. 
Games,  27. 
Ganglia,  111. 
Gastric  artery,  65. 
Gastric  juice,  38. 
Gelatine,  52. 
General  sensations,  133. 
Glands,  43. 

Salivary,  35. 

Oil,  98. 

Pancreas,  46. 

Spleen,  46. 

Liver,  44. 


154 


INDEX. 


Glands,  Lymphatic,  44,  74. 

Glosso-pharyngeal  nerve,  110. 

Gluten,  52. 

Glycogen,  45. 

"  Gooseflesh,"  96. 

Gums,  34. 

Gymnastic  exercises,  27. 

Habit,  Force  of,  141. 

Hair,  97,  105. 

Handkerchief  bandage,  78. 

Harvey,  William   (born   1578,   died 

1657),  2. 

Haversian  canals,  7. 
Heart,  Cavities  of,  60. 

Auricles  of,  60. 

Ventricles  of,  61. 

Valves  of,  61. 

Structure  of,  62. 

Sounds  of,  63. 

Size  and  shape  of,  60. 
Heart-burn,  120. 
Hemoglobin,  70. 
Hepatic  artery,  44. 

duct,  44. 

veins,  44. 
Hip  joint,  18. 
Hippocrates,  1. 
Horseback  riding,  27. 
Humerus,  13. 
Humors  of  the  eye,  124. 
Hunger,  134. 
Hygiene  denned,  1. 
Hyoid  bone  (os  hyoides),  12. 
Hypoglossal  nerve,  110. 

Ileum,  40. 

Images,  125. 

Incus,  129. 

Inferior  maxillary  bone,  11. 

turbinated  bone,  11. 

vena  cava,  60. 
Innominata  artery,  65. 

bone,  12. 


Inspiration,  86. 
Intestines,  Small,  39. 

Large,  41. 

Structure  of,  40,  41. 
Iris,  123. 

Jacob's  membrane,  124. 
Jaw  bones,  11. 
Jejunum,  39. 
Joints,  16. 

Kidneys,  102. 
Knee  cap,  14. 
Knee  joint,  18. 

Lachrymal  bones,  11. 

gland,  121. 

sac  and  duct,  122. 
Lacteals,  49,  75. 
Lacunae,  7. 
Larynx,  82. 
Laudanum,  142. 
Leg  bones,  13. 
Legumin,  52. 
Lens,  Crystalline,  124. 
Ligaments,  16. 
Liquor  sanguinis,  70. 
Liver. 

Location,  size,  and  shape  of,  44. 

Structure  of,  44. 

Uses  of,  45. 
Lumbar  vertebrae,  12. 
Lungs,  85. 
Lymphatic  vessels  and  glands,  44,  74. 

Malar  bone,  11. 

Malleus,  129. 

Marrow,  6. 

Mastication,  37. 

Medulla  oblongata,  107. 

Membranes,  Mucous  and  serous,  98. 

Metacarpus,  13. 

Metatarsus,  14. 

Middle  ear,  128. 

Milk  teeth,  33. 


INDEX. 


155 


Mitral  valve,  61. 

Molar  teeth,  34. 

Mucous  membrane,  84,  98,  99. 

Muscles,  Sizes  of,  20. 

Shapes  of,  20. 

Uses  of,  23. 

Number  and  names  of,  20. 

Strength  of,  24. 

Structure  of,  21. 

Nails,  97,  105. 

Narcotics,  142. 

Nasal  duct,  122. 

Nasal  cavities,  132. 

Near-sightedness,  127. 

Nerves,  Structure  of,  109,  111. 

Nervous  system,  105,  112,  116. 

Nitrogen,  88. 

Nitrogenous  substances,  51. 

Occipital  bone,  11. 
Oil  glands,  98. 
Old  people,  15. 
Olfactory  nerve,  110, 132. 
Opium,  142. 
Optic  nerve,  110. 
Orbits,  121. 
Organ,  defined,  2. 
Os  calcis,  14. 
Os  hyoides,  12. 
Oxygen,  88. 

Pain,  134. 
Palate  bone,  11. 
Pancreas,  46. 
Papillae,  133. 
Parietal  bone,  11. 
Patella,  14. 
Pathetic  nerve,  110. 
Pelvis,  12. 
Pepsin,  39. 
Pericardium,  62. 
Perilymph,  130. 
Periinysium,  22. 


Periosteum,  8. 
Permanent  teeth,  33. 
Perspiration,  97, 101. 
Phalanges,  13,  14. 
Pharynx,  31,  36. 
Physiology  defined,  1. 
Pia  mater,  106. 
Pigment  of  hair,  96. 

of  skin,  95. 
Pleura,  86. 

Pneumogastric  nerve,  110. 
Poisons,  147. 
Pons  Varolii,  107. 
Popliteal  artery,  65. 
Pores,  97. 

Portal  vein  and  circulation,  44,  72. 
Posture,  Erect,  15. 
Pulse  tracing,  73. 
Pupil  of  eye,  123,  124. 
Pylorus,  38,  48. 

Quality  of  food,  53. 
Quantity  of  food,  53. 
Quinsy,  32. 

Radius,  13. 

Rate  of  respiration,  88. 

of  circulation,  74. 
Rectum,  41. 
Reflex  action,  113,  115. 
Regularity  in  eating,  55. 
Respiration,  86. 
Rest,  25. 
Retina,  123. 
Ribs,  11. 
Rods  of  Corti,  130. 

Sacrum,  12. 
Salivary  glands,  35. 
Salt,  56. 
Scaphoid,  13. 
Scapula,  11. 
Sclerotic  coat,  123. 
Secretion,  100. 


156 


INDEX. 


Semicircular  canals,  129. 
Semilunar  bone,  13. 
Semilunar  valves,  61. 
Sensation,  general,  133. 
Serous  membranes,  99,  100. 
Shin  bone,  13. 
Shoulder  joint,  18. 
Sinews,  21. 
Skeleton,  8. 
Skin,  Layers  of,  95. 

Muscles  of,  96. 

Uses  of,  96. 

Glands  of,  96. 
Sleep,  117. 
Small  intestines,  39. 
Smell,  132. 

Smoking.     See  Tobacco. 
Sound,  130. 
Sounds  of  heart,  63. 
Sphenoid  bone,  11. 
Spinal  accessory  nerve,  110. 

canal,  12. 

column,  12. 

cord,  109,  114. 

nerves,  110. 
Spleen,  46. 
Sprains,  149. 
Stapes,  129. 
Starch,  51. 
Sternum,  11. 
Stimulants,  142. 
Stomach,  Location  of,  37. 

Coats  of,  38. 
Strength  of  muscles,  24. 
Structure  of  any  organ.     See  names 

of  the  respective  organs  in  Index. 
Sublingual  gland,  36. 
Submaxillary  gland,  36. 
Sugar,  51. 
Sunstroke,  148. 
Superior  maxillary  bone,  11. 

vena  cava,  60. 
Sweat  glands,  97. 
"  Sweetbread,"  46. 


Sympathetic  nerves,  111. 
Synovia,  18. 
System,  denned,  3. 

Tarsus,  14. 
Taste,  133,  136. 
Tea,  56,  118. 
Tears,  121. 
Teeth,  31,  33. 

Kinds  of,  33,  34. 

Structure  of,  34. 

Development  of,  34. 

Uses  of,  35. 

Care  of,  57. 
Temperature,  133. 
Temporal  bone,  11. 
Temporary  teeth,  33. 
Tendons,  21. 
Thigh  bone,  13. 
Thirst,  Sensation  of,  134. 
Thoracic  duct,  49,  75. 
Thorax,  12. 
Thyroid  cartilage,  83. 
Tibia,  13. 
Tight  clothing,  15. 
Tissue,  defined,  2. 
Tobacco,  29,  56,  93,  118,  135,  140. 
Tongue,  133. 
Tonsils,  31. 
Touch,  133. 
Trachea,  84. 
Tricuspid  valve,  61. 
Trifacial  nerve,  110. 
Tympanic  membrane,  129,  131. 
Tympanum,  128. 

Ulna,  13. 

Unciform  bone,  13. 
Uvula,  31. 

Valves  of  heart,  61. 

of  veins,  68. 

Pyloric,  38,  48. 
Veins,  64,  66. 


INDEX. 


157 


Ventilation,  91. 
Ventricles  of  brain,  108. 

of  heart,  61. 

Vermiform  appendix,  41. 
Vertebra,  12. 
Vestibule,  129. 
Villi,  40. 

Vitreous  humor,  124. 
Vocal  cords,  84. 


Voice,  83,  88. 
Vomer,  11. 

Walking  as  exercise,  27. 
Warm  drinks,  55. 
Waste  and  repair,  102. 
Water,  52. 
Windpipe,  84. 
Work  and  worry,  117. 


THE    END. 


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